CBSE Class 11-science Physics Work, Energy and Power
- why is force attractive when the separation between body and force increases and potential increases and vice versa? why is force repulsive when separation between body and force increases and potential decreases? if PE/force is negative why attraction and if PE/force is positive why there is repulsion? pls explain and prove the above points with suitable examples.
- State the law of conservation of energy.
- An airplane with a mass of 2000 kg sinks 1000 metres moving forward a horizontal distance of 10,000 metres. What will be its new potential energy? (Take g = 10 m/s2)
- What is the source of the kinetic energy of the falling rain drop?
- Explain why the water at the foot of the waterfall is at different temperature from that at the top?
- A body is moving with the speed of 30 m/s. How high can it be lifted to gain an amount of potential energy equal to its kinetic energy. (Take g = 10 m/s2)
- A body falling from the height of 10 m rebounds from the hard surface. It loses 20% of its energy in impact. What is the height to which it would raise after the impact and where this energy goes after hitting the surface?
- Two springs have force constants k1 and k2 where k1 > k2. On which spring, more work is done if they are stretched by the same magnitude of force.
- If a block attached to a spring (whose one end is fixed) is pulled up to a distance xo and released, the amplitude of its motion cannot exceed why?
- Draw a plot of spring force versus displacement x. Hence find an expression for the P.E of an elastic spring.
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