Question

A ball is gently dropped from a height of 20 m onto a hard surface where it make an elastic collision . If frictional looses are very small , it returns to its original height and continues to bounce up and down . . Why isn't the acceleration at the top point of the bll zero . Please answer !!!

Answer 1

Due to the action of gravitational force the acceleration can't be zero .

Explanation :

• Since we know that acceleration is rate of change of velocity .
• While the velocity is changing continuously it may become zero while changing the direction , this doesn't mean that acceleration becomes zero .
• Here the ball is gently dropped from 20 m height and bounces up and down and reaches the same height .
• The acceleration at the top can,t be zero because gravitational force is acting on it and the ball is having a certain mass .

Hence the acceleration of the ball must have some value .

Answer 2

Answer:

ANSWER

Height, s=20m

Acceleartion , a=10m/s2

By 3rd equation of motion 

v2=u2+2as

v2=0+2×10×20=400

⇒v=20m/s

So, we conclude final velocity , v=20m/s

again, by 1st equation of motion , v=u+at

⇒t=av−u

⇒t=1020=2s

So, it will strike the ground after 2s

is answer of question

Step-by-step explanation:

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