Set 4 Problem number 12

• Problem

• Solution 

• Generalized Solution

Problem

7.5 seconds after being released from rest what will be the velocity of an object which accelerates freely under the influence of the gravitational field at the surface of Earth?

Solution

In 7.5 seconds, an object accelerating from rest at 9.8 m/s^2 will attain a speed of 9.8 m/s/s * 7.5 seconds = 73.5 m/s.

Generalized Solution

In a constant acceleration situation, change in velocity is equal to the product of acceleration and time interval. 

• It follows that in a time interval of duration `dt an object accelerating under the influence of constant gravitational acceleration g will change its velocity by

• `dv = g `dt.

• Starting from rest the velocity attained will be equal to the change `dv.