- Classical Mechanics
- Conservation Laws
- Conservation of Energy
work done and conservation of energy
1. An iron ball having a mass of 5 kg is lifted from the floor to a height of 2.5 meters above the floor.
a) How much work was done to lift the ball?
b) How much potential energy did the ball gain?
2. If a 600 kg car is moving with a speed of 25 m/s, that what is its kinetic energy? Put your answer in Joules.
3. A 200 g ball is thrown upwards with an initial kinetic energy of 10 Joules. What maximum height will the ball attain? (neglect air resistance)
4. If a 200 g ball is dropped from 100 meters what is its velocity just before it hits the ground? What is its velocity after it has fallen halfway to the ground (50 m)? (neglect air resistance)
See the attached file for detailed solution.
1. a) The force needed to lift an object at constant speed is equal to its weight. So you need to apply F = mg to the iron ...
The solution explains how to calculate the work done when lifting a ball to certain height. It also applies the conservation of energy to find the speed of the ball and the maximum height.