Question

A ball of 10kg falls from rest from a height of 150m, Neglating air resistance, calculate its kinetic energy after falling a distance of 40m. Take g=10m/s

Answer 1

Answer:
`3920\ J`

Step-by-step explanation:

Given

mass of ball m=10 kg

It is placed at a height of 150 m

It is dropped from the height and allowed to free fall for 40 m

Velocity acquired by the ball during this fall is given by
`v^2-u^2=2as`

Insert u=0, a=g

`\Rightarrow v^2-0=2* 9.8* 40\\\Rightarrow v=√(784)\\\Rightarrow v=28\ m/s`

Kinetic energy at this instant

`K.E.=(1)/(2)* 10* 28^2\\\\\Rightarrow K.E.=3920\ J`