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संबंधित प्रश्न
Why is a jack screw provided with a long arm?
State two conditions when no work is done by a force.
The moon is revolving around the earth in a circular path. How much work is done by the moon?
State the S.I. unit of energy.
Give reasons for the following A teacher moving around in the class is doing work but a child standing and reading a book is not doing any work.
Express joule in terms of erg.
What do you mean by degradation of energy?
State the SI unit of work.
A cricket ball is thrown up from the earth's surface. What happens to its P.E.
(a) during the motion
(b) at the highest point?
Calculate the amount of work done by a child carrying a bag of 20 kg when he moves a distance of 40 m in
(a) Vertical direction, and
(b) Horizontal direction
Fill in the boxe to show the corresponding energy transformation.
State the energy changes which take place when A toy car with a wound spring moves on ground.
(i) A 200g ball is thrown vertically upward with an initial velocity of 30 ms-1. Draw a velocity-time graph for the motion of ball.
(ii) How long will the ball take to reach the highest point?
(iii) What will be the kinetic energy of ball, when it returns to the starting point, neglecting the air resistance?
(iv) What will be the potential energy of ball at highest point?
Calculate the work done when:
A 5 kg weight is lifted 10 m vertically. (g = 9.8 m/s2)
A force is applied on a body of mass 20 kg moving with a velocity of 40 ms−1. The body attains a velocity of 50 ms−1 in 2 seconds. Calculate the work done by the body.
Mention whether work is done or not in the following activity.
| S. No | Activity | Work done or not done |
| 1. | Pushing the door | |
| 2. | Holding a doll | |
| 3. | Sitting in a bus | |
| 4. | Pushing a wall | |
| 5. | Digging soil |
