Set 4 Problem number 12

• Problem

• Solution 

• Generalized Solution

Problem

What will be its velocity 7 seconds after being released from rest if an object accelerates freely under the influence of the gravitational field at the surface of Earth?

Solution

In 7 seconds, an object accelerating from rest at 9.8 m/s^2 will attain a speed of 9.8 m/s/s * 7 seconds = 68.6 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.