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प्रश्न
Name the type of energy possessed by a
(i) stretched catapult (ii) hot iron
(iii) wound up clock
उत्तर
(i) Potential energy
(ii) Heat energy
(iii) Potential energy
APPEARS IN
संबंधित प्रश्न
Work done = Force × ........................................
State two conditions when no work is done by a force.
In which of the following cases is work being done:
- A boy pushing a heavy rock
- A boy climbing up the stairs
- A coolie standing with a box on his head
- A girl moving on the road.
State two factors on which the work done on a body depends.
Find the kinetic energy of a body of mass 1 kg moving with a uniform velocity of 10 m s-1.
Explain degradation of energy by taking two examples of your daily life.
Is it possible that a force is acting on a body but still the work done is zero? Explain giving one example.
A boy throws a rubber ball vertically upwards. What type of work, positive or negative, is done : by the force applied by the boy?
(a) by the force applied by the boy?
(b) by the gravitational force of earth?
When do we say that work is done? Write the formula for the work done by a body in moving up against gravity. Give the meaning of each symbol which occurs in it.
A force of 50 N acts on a body and moves it a distance of 4 m on horizontal surface. Calculate the work done if the direction of force is at an angle of 60° to the horizontal surface.
A max X goes to the top of a building by a vertical spiral staircase. Another man Y of the same mass goes to the top of the same building by a slanting ladder. Which of the two does more work against gravity and why?
A block of mass 20 kg is pulled up a slope (fig.12) with a constant speed by applying a force of 500 N parallel to the slope. A and B are initial and final positions of the block.
(a) Calculate the work done by the force in moving the block from A and B.
(b) Calculate the potential energy gained by the block.
State the energy changes which take place when A piece of magnesium wire is burnt in a jar of oxygen.
Give an example
Electrical energy changes to heat energy.
A body of mass 60 kg has the momentum 3000 kgm/s-1. Calculate: the speed of the body.
A bucketful of water is to be drawn from a well ______ will be done when a ______ is applied to do this because there will be a ______ of water.
(displacement, work, force)
If a ball is dropped on the sloping roof of a house, it acquires ______ and falls on the ground. That is the transformation of ______ energy into ______ energy takes place.
(kinetic, potential, motion)
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
A wind-mill is lifting water from a well.
A proton is kept at rest. A positively charged particle is released from rest at a distance d in its field. Consider two experiments; one in which the charged particle is also a proton and in another, a positron. In the same time t, the work done on the two moving charged particles is ______.
