The Radiant way School

Raipur

PHYSICS WORKSHEET-FORCE AND WORK ,POWER AND ENERGY

Class 10 - Physics

1. A uniform metre scale is kept in equilibrium when supported at the 60 cm mark and a mass M is suspended from the 90
cm mark as shown in the figure. State with reasons, whether the weight of the scale is greater than, less than or equal to
the weight of mass M.
2. A man can open a nut by applying a force of 150 N by using a lever handle of length 0.4 m. What should be the length of
the handle, if he is able to open it by applying a force of 60 N?
3. Give any two effects of a force on a non-rigid body.
4. One end of a spring is kept fixed while the other end is stretched by a force as shown in the diagram

i. Copy the diagram and mark on it the direction of the restoring force.
ii. Name the instrument.
5. What do you mean by the terms
i. Static equilibrium and
ii. Dynamic equilibrium?
6. A stone of mass m is rotated in a circular path with a uniform speed by tying a string with the help of your hand. Answer
the following questions:
i. Is the stone moving with a uniform or variable speed?
ii. Is the stone moving with a uniform acceleration? In which direction does the acceleration act?
iii. What kind of force acts on the hand and state its direction?
7. i. With reference to the direction of action, how does a centripetal force differ from a centrifugal force during uniform
circular motion?
ii. Is centrifugal force the force of reaction of centripetal force?
iii. Compare the magnitudes of centripetal and centrifugal force.
8. A very small stone is placed near the periphery of a circular disc which is rotating about an axis passing through its
centre.
i. What will be your observation when you are standing outside the disc? Explain.
ii. What will be your observation when you are standing at the centre of the disc? Explain.
9. i. Which of the following remains constant in uniform circular motion, speed or velocity or both?
ii. Name the force required for uniform circular motion. State its direction.
10. i. Where is the centre of gravity of a uniform ring situated?
ii. The position of the centre of gravity of a body remains unchanged even when the body is deformed. State whether
the statement is true or false.
11. Draw sketch diagram and indicate the position of the centre of gravity of

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 i. sphere (solid or hollow)
ii. triangular lamina
iii. parallelogram
iv. cylinder
12. A uniform circular motion is an accelerated motion, explain using diagram.
13. A uniform meter scale rests horizontally with a hard massless string at the 60 cm mark when a mass of 10 g is suspended
from one end. From which end this mass be suspended? What is the mass of the meter scale?
14. Figure shows a uniform meter rule weighing 100 gf pivoted at its centre O. Two weights 150 gf and 250 gf hang from
the meter rod as shown in the figure.
Calculate
i. the total anti-clockwise moments about O.
ii. the total clockwise moments about O.
iii. the difference of anti-clockwise and clockwise moments about O.
iv. the distance O, where a 100 gf weight should be placed to balanced the meter rule.

15. A uniform meter scale of mass 60 g, carrier masses of 20 g, 30 g and 80 g from points 10 cm, 20 cm and 90 cm marks.
Where must be the scale hanged with string to balance the scale.
16. A spring is kept compressed by a small trolley of mass 0.5 kg lying on a smooth horizontal surface as shown in the
figure given below:

When the trolley is released, it is found to move at a speed of 2 ms-1. What potential energy did the spring posses when
compressed?
17. i. When does a force do work?
ii. What is the work done by the Moon when it revolves around the Earth?
18. Give one example of each when:
i. Chemical energy changes into electrical energy.
ii. Electrical energy changes into sound energy.
19. Mention any two differences between nuclear energy and chemical energy.
20. A boy weighing 40 kgf in 4 minute and a girl weighing climbs up a stair of 30 steps each 20 cm high 30 kgf does the
same in 3 minutes. Compare
i. the work done by them
ii. the power developed by them.
21. The potential energy of a freely falling object decreases progressively.
Does this violate law of conservation of energy? If no/yes, then why?

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22. 6.4 kJ of energy causes a displacement of 64 m in a body in the direction of force in 2.5 seconds. Calculate:
i. The force applied.
ii. Power in horse power. (1 H.P. = 746 Watts)
23. An object of mass m is allowed to fall freely from a point A as shown in the figure. Calculate the total mechanical
energy of object at:
i. Point A
ii. Point B
iii. State the law which is verified by your calculations.

24. A body of mass 50 kg has a momentum of 3000 kg ms-1. Calculate:

i. the kinetic energy of the body.
ii. the velocity of the body.
25. A girl of mass 40 kg runs up stairs and reaches the 8 m high first floor in 5s. Determine
i. the force of gravity acting on the body.
ii. the work done by her against the gravity.
iii. the power spent by the girl.
26. If a man raises a box of 50 kg mass to a height of 2 m, while the other man raises the same box to a same height in 5
min. Compare
i. the work done.
ii. the power developed by them.
27. If a body of mass m is moving with velocity v, then derive an expression for its kinetic energy.
28. In each of the following a force, F is acting on an object of mass m. The direction of displacement is from West to East
shown by the longer arrow. Observe the diagrams carefully and state whether the work done by the force is negative,
positive or zero.

29. Explain, how the work is related to direction of force and displacement.
30. Illustrate the law of conservation of energy by discussing the energy changes which occur when we draw a pendulum
bob to one side and allow it to oscillate. Why does the bob eventually come to rest? What happens to its energy

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eventually? Is it a violation of the law of conservation of energy?

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