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प्रश्न
A bullet fired against a window glass pane makes a hole in it without any cracks while a stone striking the same glass pane smashes it; explain with reason.
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उत्तर
When the bullet strikes the glass, the part of the glass coming in contact with the bullet immediately shares the large velocity of the bullet and makes a hole in it while the rest of the glass pane, due to the inertia of rest, remains at rest and so is not smashed. But when a stone strikes the same glass pan, the surrounding part of the glass gets time to share the comparatively low velocity of stone and so it is smashed.
संबंधित प्रश्न
A satellite revolves around the earth in a circular orbit. What is the work done by the force of gravity? Give reason.
Differentiate between work and power.
Name the quality which is measured in kW.
State the condition when the work done by a force is negative. Explain with the help of examples.
A boy takes 3 minutes to lift a 20 litre water bucket from a 20 m deep well, while his father does it in 2 minutes. Compare:
- the work, and
- power developed by them.
State the condition when the work done by the force is positive
A man weighing 700 N runs up a flight of 15 steps, each 20 cm high, in 5 seconds. Calculate the power of the man.
A man raises a box of mass 50 kg to a height of 2 m in 20 s, while another man raises the same box to the same height in 50 s. Compare:
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