Question

A ball is tossed vertically upwards with a speed of 5.0 m s–1. After how many seconds will the ball return to its initial position?

Answer 1

Answer:

1.02 seconds

Explanation:

Initial velocity = u = 5 m/s

t = Time taken

s = Displacement travelled = 0

a = Acceleration due to gravity = -9.81 m/s² (negative sign due to direction)

Equation of motion

$s=ut+\frac{1}{2}at^2\\\Rightarrow 0=5t+\frac{1}{2}-9.81\times t^2\\\Rightarrow 0=5t-4.905t^2\\\Rightarrow 0=t(5-4.905t)\\\Rightarro 0=5-4.905t\\\Rightarrow t=\frac{-5}{-4.905}=1.02\ seconds$

So, time taken to return to its initial position is 1.02 seconds