While catching a cricket ball of mass 0.2 kg moving with the speed of 20 m/s . The player draws his hand backward through 20 cm. Find the work done in catching the ball ?
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Answer:
W = - 40 J .
Explanation:
Given :
Mass of cricket ball is 0.2 kg
Initial velocity ( u ) = 20 m / sec .
Displacement ( s ) = 20 cm or 0.2 m
From work energy theorem :
Change in kinetic energy is equal to work done .
W = 1 / 2 m ( v² - u² )
When ball got catched final velocity become zero
i.e. v = 0
W = 1 / 2 × 0.2 × - 20²
W = - 400 × 0.1 J
W = - 40 J .
Negative sign denoted work done in opposite direction .
There is no use of displacement , it would useful when Force have asked in question .
Simply apply for Force :
F = W / s
F = 40 / 0.2
F = 200 N .
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