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प्रश्न
What are the uses of mechanical energy?
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उत्तर
- In hydroelectric plants, the kinetic energy of water is converted into electrical energy.
- Windmills convert the kinetic energy of winds into electrical energy.
- The mechanical energy of the hammer is used to apply a force to a nail.
- Mechanical energy can bring a moving body to rest and make a body at rest move.
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संबंधित प्रश्न
The kinetic energy of an object of mass m moving with a velocity of 5 m s−1 is 25 J. What will be its kinetic energy when its velocity is doubled? What will be its kinetic energy when its velocity is increased three times?
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A cyclist doubles his speed. How will his kinetic energy change: increase, decrease or remain same?
A bullet of mass 50 g is moving with a velocity of 500 m s−1. It penetrated 10 cm into a still target and comes to rest. Calculate:
- the kinetic energy possessed by the bullet, and
- the average retarding force offered by the target.
A horse and a dog are running with the same speed. If the weight of the horse is ten times that of the dog, What is the ration of their kinetic energies?
The momentum of a bullet of mass 20 g fired from a gun is 10 kg.m/s. The kinetic energy of this bullet in kJ will be :
A car of mass 120 kg is moving at a speed 18 km/h and it accelerates to attain a speed of 54 km/h in 5 seconds. Calculate:
- the work done by the engine.
- the power of the engine.
If the mass as well as the velocity of a body is doubled then the kinetic energy of the body ______ the initial kinetic energy.
Find the kinetic energy of a body of mass 5 kg moving with a uniform velocity of 10 m s-1.
A ball of mass 0.5 kg slows down from a speed of 10 m s−1 to that of 6 m s−1. Calculate the change in the kinetic energy of the ball.
