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प्रश्न
उत्तर
Principle of moments: If a body is in equilibrium under the action of number of force, then the sum of clockwise moments is equal to the sum of anticlockwise moments.
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संबंधित प्रश्न
A boy weighing 25 kgf climbs up from the first floor at height 3 m above the ground to the third floor at height 9m above the ground. What will be the increase in his gravitational potential energy? (Take g = 10 N kg -1)
A car is running at a speed of 15 km h-1 while another similar car is moving at a speed of 45 km h-1. Find the ratio of their kinetic energies.
Is it possible that a force is acting on a body but still the work done is zero? Explain giving one example.
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 boy tries to push a truck parked on the roadside. The truck does not move at all. Another boy pushes a bicycle. The bicycle moves through a certain distance. In which case was the work done more : on the trick or on the bicycle? Give a reason to support your answer.
Why is the work done on an object moving with uniform circular motion zero?
Choose one or more correct alternatives.
Joule is the unit of ______.
- force
- work
- power
- energy
Give two examples of work done.
State the energy changes which take place when Water stored in the dam is used to turn turbine in dynamo.
Give an example
Chemical energy changes to heat energy.
A body of mass 60 kg has the momentum 3000 kgm/s-1. Calculate: the speed of the body.
In what way does an ‘Ideal machine’ differ from a ‘Practical machine’?
How long should an electric motor, of power 2 H.P. operate, so as to pump 5 m3 of water from a depth of 15m. [Take g = 10 N kg−1]
A water pump raises 50 kg of water through a height of 25 m in 5s. Calculate the power supplied by the pump (Take: g = 10 N kg−1).
A is a push or a pull ______.
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
Food grains are getting dried in the sun.
