Question

A stone is thrown down off a bridge with a velocity of 7.2m/s. What is its velocity after 4 seconds have passed

Answer 1

Given :-

Initial velocity = 7.2 m/s

Time passed away = 4 sec

To Find :-

The velocity after 4 seconds have passed.

Analysis :-

Here, we are given with the initial velocity and time required.

Substitute the given values in the formula first equation of motion and find the final velocity accordingly.

Solution :-

We know that,

• u = Initial velocity
• a = Acceleration
• t = Time
• v = Final velocity
• g = Acceleration due to gravity

Using the formula,

$\underline{\boxed{\sf First \ equation \ of \ motion=v=u+at}}$

Given that,

Initial velocity (u) = 7.2 m/s

Time passed away (t)  = 4 sec

Acceleration due to gravity (g) = -9.81 m/s²

Substituting their values,

v = -7.2 - 9.8(4)

v = -7.2 - 39.2

v = -46.4 m/s

Therefore, the final velocity is -46.4 m/s.