Question

A ball with an unknown mass m is tied to a string and hung from the ceiling so that it rests against a block that has a mass of 1.2 kg. The ball is pulled back, raising it by 0.80 m, and released from rest. The ball then swings down and collides with the block. After the collision the block has a velocity of 1.0 m/s to the right on the frictionless surface, while the ball rebounds to a height of 0.20 m. Use g = 10 m/s2. 1.2 kg. Calculate the speed of the ball just before the collision.

Answer 1

v = 3.96 m/s

Step-by-step explanation:

given,

mass of the ball = 1.2 kg

ball raised to the height = 0.80 m

ball is released from rest

velocity of the block after collision = 1 m/s

ball rebound height = 0.2 m

acceleration due to gravity = 10 m/s²

using energy conservation

`mgh = (1)/(2)mv^2`

`gh = (1)/(2)v^2`

`9.8 * 0.8 = (1)/(2)v^2`

`v = √(2* 9.8* 0.8)`

v = 3.96 m/s

the speed of the ball just before the collision is equal to v = 3.96 m/s