National Book Foundation (FBISE)
Conceptual Question Solution ( 1-7 )
Table of Content
UNIT # 01
PHYSICAL QUANTITIES AND MEASUREMENTS
Conceptual Questions
Q No 01. “Physics has made our live comfortable” Justify this statement.
Answer
No doubt in a lot of ways physics has made our lives more comfortable. The discoveries or inventions of electricity, wireless communication, X-rays, computers, automobiles etc. have affected our lives in a way that we no longer can imagine our life without the technologies developed using the medium of Physics.
Q No 02. What base quantities are involved in these derived physical quantities?Force, Pressure, Power and charge
Answer
Force
F = ma
F= kg m /s2
Force= Mass × Displacement
In force base quantities Mass, displacement and Time are involved .
Power
P = 𝑊 𝑡
“W” represents work
P = 𝐹×𝑠 𝑡
P= 𝑚𝑎 ×𝑠 𝑡
P = 𝐾𝑔 𝑚 ×𝑚 𝑠×𝑠 2
P = 𝐾𝑔×𝑚2 𝑠 3
Power = 𝑀𝑎𝑠𝑠 ×𝐷𝑖𝑠𝑝𝑙𝑎𝑐𝑒𝑚𝑒𝑛𝑡2 𝑇𝑖𝑚𝑒3
In Power base quantities Mass, displacement and Time are involved
Pressure
p = 𝐹 𝐴
“F” represent Force
p= 𝑚𝑎 𝐴
p= 𝑘𝑔𝑚 𝑚2𝑠 2
p= 𝑘𝑔 𝑚𝑠 2
power = 𝑀𝑎𝑠𝑠 𝐷𝑖𝑠𝑝𝑙𝑎𝑐𝑒𝑚𝑒𝑛𝑡×𝑇𝑖𝑚𝑒2
In force base quantities Mass, displacement and Time are involved
Charge
As I = 𝑄 𝑡
“Q” represent Electric Charge
Q = I × t Q = Ampere × second Charge = Electric Current × Time
In Charge Base quantity Electric Current and Time are involved
Q No 03. Show that prefix micro is thousand times greater than prefix nano.
Answer
As we know that micro = 10-6 and nano = 10-9
Now 𝑚𝑖𝑐𝑟𝑜 𝑛𝑎𝑛𝑜 = 10−6 10−9 = 10-6 × 10+9 = 10 -6+9 = 10 3 = 1000
Therefore micro is thousand times greater than prefix nano.
Q No 04. Screw Gauge can give more precise length than Vernier calliper. Briefly explain why?
Answer
As we know that least count of Vernier calliper is 0.02mm with 50 div on Vernier scale, which shows that it measures accurately up to 50th part of a millimetre and least count of screw gauge is 0.01mm with 50 div on circular scale, which shows that it measure accurately up to 100th part of a millimetre. Therefore screw Gauge give more precise length as compare to Vernier calliper.
Q No 05. Differentiate between mechanical stop watch and digital stop watch.
Answer
Mechanical stop watches are powered by a mainspring. The least count of a mechanical stop watch we have used in the laboratory is 0.1 seconds. Digital stop watches are powered by Batteries. The least count of a digital stop watch we have used in the laboratory is 0.01 seconds. Digital stop watches due to their crystal oscillator timing element, are much more accurate than mechanical stop watches.
Q No 06. How measuring cylinder is used to measure volume of an irregular shaped stone?
Answer
Take as measuring cylinder filled with water and note the first reading. Now immersed the object completely and note the reading again. The volume of the object is found by subtracting the first reading from second.
Q No 07. What precautions should be kept in mind while taking measurement using measuring cylinder?
Answer
Make sure the measuring cylinder is placed on a flat surface. While observing the liquid meniscus the line-of-sight should be at the same horizontal level as that of the lowest meniscus. There should be no air bubble in the liquid while measuring its volume.
Q No 08: Why do we need to consider significant digits in measurement?
Answer
Because in every measurement in a lab, there are inherent errors. No measurement can be known exactly. For this reason, we write or use measurements by limiting the number of digits and write the measured value up to the significant.
UNIT # 02 KINEMATICS
Conceptual Questions
Q No 01. In a park, children are enjoying a ride on a big wheel. What kind of motion the big wheel has and what kind of motion the riders have?
Answer
Big wheel in the parks is called Ferris wheel. The motion of a Ferris wheel is rotational whereas people riding on the Ferris wheel undergoes circular motion.
Q No 02. A boy moves for some time, give two situations in which his displacement is zero but covered distance is not zero?
Answer
Yes, it is possible that displacement is zero but not the distance. When the boy moves in a circular track the displacement of the boy is zero because the boy reaches to its initial position. While the distance covered by the boy is not zero. In other situation boy walks on a straight path and comes back to the same point displacement is zero but distance is not zero.
Q No 03. A stone tied to a string is whirling in circle, what is direction of its velocity at any instant .
Answer
When a stone tied to a string is whirling in circle, velocity of stone is acting as tangent to the circle which is perpendicular to the direction of centripetal force or radius of the circle.
Q No 04. Is it possible to accelerate an object without speeding it up or slowing it down?
Answer
yes it is possible. When an object moves in a circular path with uniform circular motion, object is accelerating but its speed neither increases nor decreases.
Q No 05. Can a car moving towards right have direction of acceleration towards left?
Answer
Yes if we apply brakes on the car its speed decreases and deceleration is produced in it. In this case direction of velocity is towards right but the direction of acceleration is towards left.
Q No 06. With the help of daily examples, tell the situation in which
- acceleration is in the direction of motion
- acceleration is against the direction of motion
- acceleration is zero and body is in motion
Answer
1. If a car is moving on the straight line with increasing speed the acceleration is in the direction of motion.
2. when we apply brakes on the car its speed decreases and deceleration is produced in it. In this case the acceleration is against the direction of motion.
3. If the car is moving with uniform velocity the acceleration is zero but car is in motion .
Q No 07 Examine distance time graph of the motorcyclist (as Shown), what does the graph tell us about the speed of motorcyclist? Plot the velocity time graph for it?
Answer
This graph tells us that the speed (velocity) of the motorcyclist is uniform (constant) because it cover equal distance (displacement) in equal intervals of time. Velocity-Time graph .
Q No 08 which controls in the car can produce acceleration or deceleration in it?
Answer
Accelerator produce and controls acceleration in the car and Brakes reduce the speed of the car which produce declaration in the car.
Q No 09. If two stones of 10 kg and 1 kg are dropped from a 1km tower. Which will hit the ground with greater velocity? Which will hit the ground first? (Neglect the air resistance)
Answer
If we neglect the air resistance and just considering the gravity then both the balls will reach the ground at same time as acceleration due to gravity (g) does not depend upon the mass of the object.
Q No 10. A 1kg steel ball is dropped (from rest) and another is thrown with velocity of 5m/s, which will have greater acceleration? (Neglect the air resistance)
Answer
Both of these balls are moving under the force of gravity with an acceleration of g= 9.8m/s2 so both balls will have same acceleration which are independent of their masses.
Unit # 03 Dynamics
Conceptual Questions
Q No 01. When a motor cyclist hits a stationary car, he may fly off the motor cycle and driver in the car may get neck injury.
Answer
When a motor cyclist hits a stationary car then he cannot stop himself due to inertia and continue his state of motion so he may fly off the motor cycle. Explanation: While the driver in the car is at rest. When the motor cyclist hits the car then the upper part of the driver wants to stay at rest due to inertia, but his lower part moves with the car with a force produced of collision. So the driver in the car may get neck injury .
Q No 02. In autumn, when you shake a branch, the leaves get detached. Why does this happen?
Answer
In autumn, when we shake a branch, the leaves get detached. Because when a tree is forcefully shaken, the branches of the tree come in motion but the leaves tend to continue in their state of rest due to inertia. As a result of this, leaves get separated from the branches of the tree and hence fall down.
Q.no 03. When a car takes a turn, the passengers experience a force acting on them away from the centre of curve, why?
Answer
When a car takes a turn then centripetal force is produced which keeps the car to move in a circle. But according to Newton third law of motion, in reaction of this force centrifugal force is also produced. Due to which passengers experience a force acting on them away from the centre of curve. Secondly as the car takes the turn, according to inertia they will continue their motion is straight path and that's why they are directed away from the centre of curve instead of going towards it.
Q No 04. Why it is not safe to apply brakes only on the front wheel of a bicycle?
Answer
If we apply brakes only on the front wheel of a bicycle then the bike lifts the rear wheel which may cause of an accident. It is due to inertia that the rear wheel wants to continue its motion but when we apply brake, our weight is being shifted towards the front wheel, it stop at the spot and bicycle may overturn.
Q No 05. Deduce Newton's first law of motion from Newton's second law of motion.
Answer
According to Newton's 2nd law 𝐹 = 𝑚𝑎 𝑣𝑓 − 𝑣𝑖 𝐹 = 𝑚 𝑡 If F = O then vi = vf i.e. the object continues to move with uniform velocity if no net force is applied. If F = O & vi = vf , then vf is also 0. i.e. the object will stay at rest.
As you know that Newton's 1st law of motion states that an object at rest or uniform motion tends to remain at rest or in uninform motion unless an external applied on it. Hence proved .
Q No 06. Action and reaction are equal but opposite in direction. These forces always act in pair. Do they balance each other? Can bodies move under action-reaction pair?
Answer
Balanced forces are equal and opposite forces that act on the same object. That's why they cancel out. Action and reaction forces are equal and opposite forces that act on different objects, so they don't cancel out. No, a body cannot move under action-reaction pair. For example book lying on the table has weight downward but the table has normal reaction force in upward direction.
Q No 07. A man slips on the oily floor, he wants to move out of this area. He is alone. He throws his bag to move out of this slippery area. How can this act help him?
Answer
When a man slips on the oily floor then he has minimum friction between floor and his feet. He throws his bag to move out of this slippery area. When he throws a bag in one direction then this is an action, according to third law of motion as a reaction he will move in opposite direction due to less friction. This act helps him to move out from the oily floor.
Q No 08. How would you use Newton's 3rd law of motion and law of conservation of momentum to explain motion of rocket?
Answer
Newton's third law of motion states that to every action there is an equal and opposite reaction. Similarly, when a rocket moves, it exerts the action force on the gases to expel them backwards which in turn exerts an equal and opposite reaction force to move the rocket forward. Rocket works on the principle of Conservation of momentum. Rocket eject gases in backward direction which creates momentum of the gases backwards and thus by conservation of momentum, the rocket gets momentum in the forward direction making it move forward.
Q No 09. Why are batsman gloves padded with foam?
Answer
Batsman gloves are padded with foam for protection and it provides better friction between the gloves and the bat instead of using cotton. Foam and cotton are the types of materials that are used in the finger padding of batting gloves. Despite being lightweight, foam offers the same level of protection as cotton padding. Batsman can better hold the bat due to the finger cutouts, which add extra wrap around the handle due to enough friction between gloves and bat.
Q No 10. While walking on ice, one should take small steps to avoid slipping. Why?
Answer
To avoid slipping one should take smaller steps because the friction coefficient of ice is small. So we didn't get enough friction by the ice. Smaller steps will give larger normal force and more the normal force will give more friction and hence we get sufficient friction to avoid slipping .
Q No 11. "Slippery when wet", it is precaution displayed on motorways. Why is it dangerous to drive on wet roads?
Answer
“Slippery when wet" it is precaution displayed on motorways. The biggest hazard of driving on wet roads is the loss of grip or friction. When roads are dry they have enough friction between road and tyres. When a road is wet, the surface of the road becomes smoother which means lack of friction between road and tyres. So when the car is moving and we apply brakes then the brakes will not work properly due to lack of friction which may cause of an accident.
Q No 12. Why tyres of vehicles are wrapped with chains during snow in Murree hill areas?
Answer
Tyres of vehicles are wrapped with chains during snow in Murree hill areas because Snow chains work simply by increasing the amount of grip or friction that tyres have on the roads when they are icy or covered in snow. Increasing the friction between the car and the road makes driving much safer as it reduces the chance of cars losing control and skidding on icy surfaces .
Q No 13. Centripetal force acting on the car moving at a roundabout is 200N. If the velocity of the car is double then what will be centripetal force acting on the car?
Answer
Given
𝑭𝒄 = 𝟐𝟎𝟎𝑵
𝒗ˊ = 𝟐𝒗
To find
𝑭ˊ𝒄= ?
Calculation
𝑭𝒄 = 𝑭ˊ𝒄 = 𝒎𝒗𝟐 𝒓 𝒎𝒗ˊ 𝟐 𝒓
𝑭ˊ𝒄 = 𝑭ˊ𝒄 = 𝒎(𝟐𝒗) 𝟐 𝒓 𝒎𝟒𝒗𝟐 𝒓 𝒎𝒗𝟐
𝑭ˊ𝒄 = 𝟒 ( 𝒓 ) 𝑭ˊ𝒄= 𝟒 𝑭𝒄
Hence, if the velocity of the car is doubled then centripetal force increases by 4 times.
Q No 14. Your car is stuck in mud track, two men sit on the bonnet of your car. This helps you to take your car out of mud. How sitting of men on car's bonnet did help you?
Answer
Car stuck in mud track, two men sit on the bonnet to increase its friction. This will help to take the car out of mud. When the car stuck in wet mud the friction between tyres and mud decreases due to which car cannot move. So two men sit on the bonnet or the car to increase the normal force (Fn). Then the friction also increases which will help to take the car out of the mud.
UNIT # 04
TURNING EFFECT OF FORCES
Conceptual Questions
Q No 01. Two forces of 7N and SN are added, how will they give resultant of 12N and 2N?
Answer
Two forces 7N and SN has a resultant of 12N if they have same direction and parallel to each other. Two forces 7N and SN has a resultant of 2N if they have opposite direction and parallel to each other.
Q No 02. Why long spanner is used to open or tights nuts of vehicle’s nut, extra-long wrench is not suitable. Why?
Answer
A long spanner provides a greater moment of force than a short one hence less force is applied. That's why long spanner is used to open or tight nuts of vehicle's tyre. If we use extra-large wrench for tightening a small bolt, a large torque will produce. This may damage or break the bolt. So extra-long wrench is not suitable for tightening a small nut.
Q No 03. Why door knobs are fixed at the edge of door? What will happen if the door knob is at the middle of the door?
Answer
Door knobs are fixed at the edge of door because doors are opened through the application of torque. To make it as easy as possible to open the door, the knobs are placed as far from the hinge as is feasible. This maximizes the lever arm, reducing the amount of force needed to open the door. If the door knob is at the middle of the door then greater force is required as compared to the door knob at the edge of the door. Because the knob at the middle of the door decreases the moment arm which means greater force is required to open the door.
Q No 04. A uniform meter rod is balanced on the sharp edge of a knife. A mass is hanging on its right side. Why is it not falling on the right side?
Answer
We can see that a mass is hanging with a rod and the rod also has a mass. As torque depends upon force and moment arm so in this case the clockwise torque produced on right side is equal to the anti-clockwise torque produced on the left side of the knife. These two torques are equal so the uniform metre rod is balanced on the sharp edge of a knife.
Q No 05. How does this toy remain balanced on finger, even disturbed slightly?
Answer
Balancing bird remain balanced on finger, even disturbed slightly because of the way that the balancing bird is spreading its wings , it is able to distribute its weight in such a way that it creates a centre of gravity right below the beak. The Ce1ntre of gravity is an imaginary point in a body of matter where the total weight of the body is thought to be concentrated. Having the centre of gravity below the beak allows the bird to be balanced on a finger.
Q No 06. A small boy is thrown straight up by his father. At the top of his path, he comes to rest for a moment. Will he be in equilibrium at this point?
Answer
A small boy is thrown straight up by his father. At the top of his path, only velocity is zero but the acceleration due to gravitational force is acting downward continuously. For a body to be in equilibrium, some of all the force acting on the body must be equal to zero. So the small boy is not in an equilibrium. As you can see, it will fall under gravity and not stay in the air. If the small boy was in an equilibrium, it would not fall under gravity. Of course, that would never happen.
Q No 07. A fan is rotating uniformly, is it in equilibrium?
Answer
If a body is at rest or moving with uniform velocity then the body is in equilibrium. As the fan is rotating uniformly so it is in equilibrium.
Q No 08. Can a body be in equilibrium under the action of single force or single torque?
Answer
For a body to be in complete equilibrium, the sum of all the forces and some of all the torques acting on the body must be equal to zero. A body cannot be in the state of equilibrium if only a single force acts on it because we need two or more forces equal in magnitude but opposite in direction to cancel out each other. Since single torque can never be zero and rotational acceleration will be produced. Therefore we can say that a body cannot be in equilibrium under the action of single torque.
Q No 09. Give an example of a body, which satisfies first condition of equilibrium but it is not in equilibrium?
Answer
A pendulum at its extreme positions are not in equilibrium but under the action of the force of gravity
Q No 10. Why Heavy Transport Vehicles (HTV) are made at their bottom? Heavy Transport Vehicles (HTV) are made heavy at its bottom so that to keep its centre of gravity as low as possible.
Answer
A lower centre of gravity helps to keep the Heavy Transport Vehicles stable. Moreover, the base is made wide so that the vertical line passing through the centre of the gravity should not get out of its base during a turn .
Q No 11. A boy standing by joining both legs is more likely to fall than a boy standing with legs wide open. If slightly pushed by another boy why?
Answer
A boy standing by joining both legs is in state of unstable equilibrium. If he is slightly pushed by another boy then his canter of mass falls when it is displaced, and he will not come to its original position. Hence he may fall down. While a boy standing with open legs is in state of stable equilibrium. If he is slightly pushed by another boy then his center of mass rises when it is displaced, and he comes back to its original position. Hence he may not fall.
Unit # 05 Gravitation
Conceptual Questions
Q No 01. Newton's law of gravitation suggests that gravitational force acts between any two material objects. Then why two chairs in your room do not attract each other due to this force?
Answer
In order to be able to notice the gravitational force of attraction between any two objects, at least one of the objects on the earth should have an extremely large mass. Since no object on the earth have an extremely large mass, we cannot notice such forces. The two chairs in a room do not move towards each other due to their small masses, the gravitational force of attraction between them is very, very weak .
Q No 02. Why "G" is called universal gravitational constant?
Answer Universal gravitational constant, G is independent of the nature of the particle, medium between the particles, change in position and time. G is a constant of proportionality and called the universal gravitational constant. Its value remains same everywhere on the earth or in the universe. Value of G = 6.67 x 10-11 Nm2 kg-2 .
Q No 03. Why is it difficult to measure the value of "G"?
Answer
G is quite difficult to measure because gravity is much weaker than other fundamental forces, and an experimental apparatus cannot be separated from the gravitational influence of other bodies. The value of G is an extremely small numerical value i.e. G = 6.67 x 10-11 Nm2 kg-2 . Its smallness accounts for the fact that the force of gravitational attraction is only appreciable for objects with large mass.
Q No 04. Where will your weight be greater, at Murree hills or at Karachi? Where will your mass be greater?
Answer We know that W = mg Weight of the body depends upon the value of gravitational acceleration g which changes with altitude. As the distance from the Earth increases, the value of g decreases. Murree is at height as compare to Karachi so weight of the body is greater at Karachi then Murree hills. Mass is constant everywhere. It does not changes with change of place. So mass will same at both places.
Q No 05. If a man travels from the North Pole to the equator, what will be the effect on his weight during this trip?
Answer
We know that weight of the body depends upon the value of gravitational acceleration. The value of g is smaller at equator then the poles. So if a man travels from the North Pole to equator then his weight losses, but the difference is small. Note that the body itself does not change. Rather it is the force of gravity and other forces that change as he approaches the equator. These forces change right back when he return to your original latitude.
Q No 06. Earth and an apple on a tree attract each other by the force of gravity. The apple falls on earth but why the earth does not move towards apple?
Answer
Earth and an apple on a tree attract each other by the force of gravity. The apple falls on earth but the earth does not move towards apple because of mass. Apple falls towards the earth, but the earth does not move towards the apple because acceleration is inversely proportional to mass. Earth's mass being extremely large as compared to apple, it has negligible acceleration towards the apple. So the apple falls on the earth.
Q No 07. The mass of the moon is 100 times less than the mass of earth and the radius of the moon is 4 times less than the radius of the earth. Show that the value of g is 6 times less than the value of g on the earth?
Answer
Data
By putting value of 𝑀𝑚 𝑎𝑛𝑑 𝑅𝑚
𝑔𝑚 = 𝐺 ( 𝑀𝑒 100) ( 𝑅𝑒 4 ) 2
𝑔𝑚 = 𝐺 ( 𝑀𝑒 100) 𝑅𝑒 2 16 𝑔𝑚 = 𝐺𝑀𝑒 100 × 16 𝑅 𝑒 2 𝑔𝑚 = 16 100 × 𝐺𝑀𝑒 𝑅 𝑒 2 𝑔𝑚 = 16 100 × 𝑔𝑒 𝑔𝑚 = 1 6.2 × 𝑔𝑒 𝑔𝑚 = 𝑔𝑒 6 𝐻𝑒𝑛𝑐𝑒 𝑃𝑟𝑜𝑣𝑒𝑑 𝑀𝑚 = 𝑀𝑒 100 𝑅𝑚 = 𝑅𝑒 4 To Prove: 𝑔𝑚 = 𝑔𝑒 6 Solution: 𝐴𝑠 𝑓𝑜𝑟 𝐸𝑎𝑟𝑡ℎ, 𝑔𝑒 = 𝐺𝑀𝑒 𝑅 𝑒 2 𝑆𝑜 it will become for moon; 𝑔𝑚 = 𝐺𝑀𝑚 𝑅 𝑚 2 3
Q No 08. If mass and radius of the earth becomes double then what will be the effect on the value of g on the surface of the earth?
Answer
We know that 𝐴𝑠 𝑓𝑜𝑟 𝐸𝑎𝑟𝑡ℎ,
𝑔𝑒 = 𝐺𝑀𝑒 𝑅 𝑒 2 𝑔ˊ𝑒 = 𝐺(2𝑀𝑒 ) (2𝑅𝑒 ) 2 𝑔ˊ𝑒 = 2𝐺𝑀𝑒 4𝑅 𝑒 2 𝑔ˊ𝑒 = 1 2 ( 𝐺𝑀𝑒 𝑅 𝑒 2 ) 𝑔ˊ𝑒 = 1 2 (𝑔𝑒 ) So if mass and radius of the earth becomes double then value of ‘g’ reduce to half.
Q No 09. Artificial satellites do not have engines like cars then how can they keep on moving around the earth?
Answer
Artificial satellites do not have engines like cars but they keep on moving around the earth. We know that centripetal force keeps a body to move in a circle. So a satellite rotates around the earth by using earth's gravitational force as centripetal force. Also as there is no air in space, it does not have to work against air resistance. Hence it doesn't lose any energy while rotating.
Q No 11. The orbital speed of a satellite orbiting very to earth (at negligible height) is “vo”. What will be the orbital speed of another satellite revolving at a height, equal to the radius of earth (in term of orbital speed of close orbiting satellite).
Ans: As we know that the orbital speed of satellite is; 𝑣𝑜 = √ 𝐺𝑀 𝑅 Orbital speed at height ‘h’ is; 𝑣ˊ𝑜 = √ 𝐺𝑀 𝑅 + ℎ As ℎ = 𝑅 𝑡ℎ𝑒𝑟𝑒𝑓𝑜𝑟𝑒 𝑣ˊ𝑜 = √ 𝐺𝑀 𝑅 + 𝑅 𝑣ˊ𝑜 = 1 √2 √ 𝐺𝑀 𝑅 𝑣ˊ𝑜 = 0.707 𝑣𝑜
UNIT # 06 Work and Energy
Conceptual Questions
Q No 01. Under what condition, work done on the body is maximum and minimum?
Answer
Maximum work done: Work one will be maximum if the angle between force and displacement is zero. i.e. 𝑊 = 𝐹𝑑𝑐𝑜𝑠𝜃 = 𝐹𝑑𝑐𝑜𝑠0° = 𝐹𝑑 (1) = 𝐹𝑑 Minimum work done: Work done will be minimum if the angle between force and displacement is 90. i.e. 𝑊 = 𝐹𝑑𝑐𝑜𝑠𝜃 = 𝐹𝑑𝑐𝑜𝑠90° = 𝐹𝑑 (0) = 0
Q No 02. Why is only horizontal component of the force acting on the body involved in expression of work?
Answer
When force is applied on an object at some angle then the object covers some distance. As the object moves along the horizontal component of the force and not along the vertical component. So, it is only horizontal component of the force ‘𝐹𝑐𝑜𝑠𝜃’ acting on the body that involves in expression of work. 𝑊 = 𝐹. 𝑑 𝑊 = (𝐹𝑐𝑜𝑠𝜃). 𝑑 𝑊 = 𝐹𝑑𝑐𝑜𝑠
Q No 03. If a bucket of water having mass of 20kg is carried by a person through distance of 10m, calculate the work done by the person in carrying the bucket.
Given
To find
Calculation
Q No 04. Give an example of negative work done by a body?
Q No 05. Describe the situation in which no work is done, although force is acting on the body and it is covering some displacement.
Q No 06. A car has Kinetic energy ‘K’. What will be effect on its Kinetic energy if its velocity is doubled?
Q No 07. Why is potential energy stored in the body when it is lifted to some height from surface of earth?
Q No 08. Work done on the body either speed it up or slows it down or raises it up. Keeping in mind, tell how much work is done by centripetal force on the orbiting satellite?
Q No 09. A bullet is fired from gun, bullet penetrates into a sand wall and it stops. Where is its kinetic energy used?
- Sound energy
- Heat energy
- Displacing the sand
- Deforming the bullet