Lesson: The Work–Energy Principle
In this lesson, we will learn how to use the work–energy principle to solve problems of motion of a particle.
Sample Question Videos
Worksheet: 25 Questions • 1 Video
A body of mass 15 kg fell from a height of 15 m above the ground. Using the work-energy principle, find its kinetic energy just before it hit the ground. Consider the acceleration due to gravity to be 9.8 m/s2 .
A ring of mass 1.5 kg was sliding down a vertical pole. Starting from rest, it accelerated over a distance of 3.3 m until its speed became 6.2 m/s. Using the work-energy principle, determine the work done by the resistance to the ring’s motion. Take .
Two bullets of equal mass were fired at the same speed into the opposite sides of a target. The target was formed of two different pieces of metal stuck together. The first was 10 cm thick, and the second was 14 cm thick. When the bullets hit the target, the first one passed through the first layer and embedded 8 cm into the second before it stopped, whereas the other bullet passed through the second layer and embedded 5 cm into the first layer before it stopped. Using the work-energy principle, calculate the ratio , where is the resistance of the first metallic layer, and is that of the second.