Q7. A 2kg ball is released from a height of 20m. What is it velocity when its height has decreased to 5
m?​

Given,

Mass, m = 2kg

Height or distance, s = 20m

Initial velocity, u = 0m/s

Acceleration due to gravity, g = 10m/s (It is 9.8m/s but can be assumed 10m/s for simplifying calculations)

(Because the object is is just dropped)

Final velocity, v = ?

Solution

v^2 = u^2 + 2as (u^2 means u raised to power 2)

=> v^2 = 0^2 + 2*10*20

=> v^2 = 400

=> v = 20

Thus the velocity just before the body strikes the ground will be 20m/s.