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प्रश्न
State the law of conservation of energy.
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उत्तर
According to the law of conservation of energy, energy can neither be created nor can it be destroyed. It only changes from one form to another.
संबंधित प्रश्न
Explain briefly why the work done by a fielder when he takes a catch in a cricket match is negative.
A force acts on a body and displaces it by a distance S in a direction at an angle θ with the direction of the force. What should be the value of θ to get the maximum positive work?
A machine raises a load of 750 N through a height of 16 m in 5 s. calculate:
- energy spent by machine,
- power at which the machine works.
A box of weight 150 kgf has gravitational potential energy stored in it equal to 14700 J. Find the height of the box above the ground. (Take g = 9.8 N kg-1)
A girl of mass 50 kg runs up a flight of 40 steps in 20 seconds. If each step in 20 cm high, calculate the power developed by the girl. (g= 10 ms-2).
What should be the characteristic of a source of energy?
A block of mass 30 kg is pulled up a slope, as shown in diagram with a constant speed, by applying a force of 200 N parallel to slope.
A and B are initial and final positions of block.
(i) Calculate the work done by force in moving the block from A to B.
(ii) Calculate P.E. gained by block. [g=10ms-2]
What is work?
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
A green plant is carrying out photosynthesis.
