Question

A 1 kg ball is thrown upwards with a speed of 9.9 m/s. Calculate the work done
by its weight in one second.​

Answer 1

Given : a 1 kg ball is thrown upwards with a speed of 9.9 m/s

To Find : calculate the work done by its Weight in one second​

Solution:

Initial Velocity = 9.9 m/s

a =  g = - 9.8 m/s

V = U + at

Velocity after 1 sec =   9.9 + (-9.8)(1)

= 0.1  m/s

KE = Kinetic Energy

KE   = (1/2)mV²

KE at initial  =  (1/2)*1(9.9)²

KE after 1 sec =  (1/2)*1(0.1)²

Change in KE  =  (1/2)*1(0.1)² -  (1/2)*1(9.9)²

= (1/2) ( 0.1 + 9.9)(0.1 -9.9)

= (1/2)(10)(-9.8)

= -49 J

Work Done  = -49 J

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Answer 2

Answer is given in above 2 photos⤴