Question

One ball (A) is kicked at 30 degrees from the ground, reaches a maxium height of 8.0 m and then comes down to the ground. Another ball (B) is released from rest from the roof of a 8.0 high building. If the times of balls A and B in the air are t_A and t_B, how these times compare?

A. t_A = 1/2 t_B

B. t_A = t_B

C. t_A = 2t_B

D. t_A = 3t_B

E. t_A = 4t_B

I think the answer is B and would like to know if I'm right.

Answer 1

Vertical distance travelled by both the balls is same with same condition that is speed at the top is equal to zero

But the vertical distance travelled by ball A is twice the distance ttravelled by ball B

thus tA=2tB

hence ans is C

Answer 2

ANSWER :

Ball A remains in air for reaching maximum height 8.0m and coming down. 

Time for going up and coming down is equal. 

So, 

tA = 2 * time to come down from 8.0 m height for ball A 

Now, tB = time taken for ball B to come down 

time downward for A = time downward for B

So, 

tA = 2 tB  : Option C (ANSWER).