Question

A ball is dropped from the top of a building. It aquires a velocity of 30 m s–1   on reaching the ground. Calculate the height of the building​

Answer 1

Correct question:-

A ball is dropped from the top of a building.It acquires a velocity of 30m/s on reaching the ground.Calculate the height of the building.

Given:-

→Final velocity of the ball=30m/s

To find:-

→Height of the building.

Solution:-

In this case:-

•Acceleration due to gravity = +9.8m/s²

•Initial velocity of the ball = 0

Here,we shall use the 3rd equation of motion:-

=>v²-u²=2gh

=>(30)²-0 = 2×9.8×h

=>900 = 19.6h

=>h = 900/19.6

=>h = 45.91m

Thus,height of the building is 45.91m.

Note:-If we take g= 10m/s²,then the height of the building will come out as 45m.

Answer 2

Answer:

v = 30 ms^-2

u = 0

g = 10 ms^-2

v^2 - u^2 = 2gh

(30)^2 - (0)^2 = 2 × 10 × h

900=20h

900/ 20 = h

h = 45