Question

Ball A is dropped from the top of the building. At the same instant another identical ball B is thrown vertically upward from the ground. When the ball collide,they are moving in opposite directions and the speed of a is twice the speed of B. At what fraction of the height of the building did the collision occur​

Answer 1

Answer:

2/3

Explanation:

Ball A is dropped from the top of the building. At the same instant another identical ball B is thrown vertically upward from the ground. When the ball collide,they are moving in opposite directions and the speed of a is twice the speed of B. At what fraction of the height of the building did the collision occur​

let say both balls collide at time = t

V = u + at

u = 0 for a as dropped   a = g = 10 m/s²

Velocity of a = 0 + 10t = 10t  

Let say b is thrown with velocity b

a = -g = -10m/s²

Velocity of b  = V - 10t

10t    = 2 * (V - 10t)

=> 2V = 30t

=> V = 15t

S = ut + (1/2)at²

Distance Covered by a = 0 + (1/2)(10)² = 5t²

Distance Covered by b = 15t(t) + (1/2)(-10)t² = 10t²

Total height of building = 5t² + 10t² = 15t²

fraction of the height of the building  the collision occur​ = 10t²/15t²

= 2/3