Question

A ball thrown up vertically upwards reaches a certain height in 6 seconds. calculate the velocity with which it is thrown up, if g= 10m/s2​

Answer 1

A ball thrown up vertically upwards reaches a certain height in 6 seconds.

We have to find the velocity of the ball with which ball is thrown up.

From above data we have; height (h) is 6 m, final velocity (v) is 0 m/s [ at highest point, velocity = 0 ] and acceleration due to gravity (a) is -10 m/s [ as it is against the motion ]

First equation of motion:

v = u + at

Second equation of motion:

s = ut + 1/2 at²

Third equation of motion:

v² - u² = 2as

As we have value of v, a and s. So, using the Third Equation Of Motion i.e. v² - u² = 2as

Substitute the known values in the above formula,

→ (0)² - u² = 2(-10)(6)

→ 0 - u² = -120

→ u² = 120

→ u = 10.95

→ u = 11 (approx.)

Therefore, the initial velocity of the ball is 11 m/s.