Question

A ball is thrown from the top of a building down, which land 12.5m away from the base of the building. How tall is the building.

Answer 1

122.5 m

Step-by-step explanation:

To solve the problem, we need to know the speed at which the ball has been thrown: here I assumed it has thrown at a speed of

`v=2.5 m/s`

The motion of the ball is a projectile motion, so it consists of two independent motions:

- A uniform motion along the horizontal direction

- A uniformly accelerated motion along the vertical direction

We know that the ball lands at a distance of

d = 12.5 m

away from the base of the building; so the time taken by the ball to cover this distance in the horizontal direction is

`t=(d)/(v)=(12.5)/(2.5)=5 s`

The vertical distance covered by the ball is given by the suvat equation

`s=(1)/(2)gt^2`

where

`g=9.8 m/s^2` is the acceleration due to gravity

Therefore, substituting t = 5 s,

`s=(1)/(2)(9.8)(5)^2=122.5 m`

So, the height of the building is 122.5 m.