Question

A ball is thrown vertically upwards and rises to a height of 15 m. Calculate the initial velocity at which the object was thrown upwards and the time taken by the ball to reach the highest point?

1. 1.74 s
2. 2 s
3. 3.76 s
4. 1.58 s

Answer 1

Correct Answer - Option 1 : 1.74 s

The initial velocity of ball u = ?

The final velocity of ball v = 0

Distance s = 15 m

Acceleration a = -g = -9.8 m/s²

By using 2nd law of motion,

v² = u² + 2as

0 = u² + 2 (-9.8)(15)

u = 17.146 m/s

To find the time, we will use 1st law of motion,

v = u + at

0 = 17.146 + (-9.8)t

t = 17.146 / 9.8

t = 1.74 s