[طالبه حزينه]

Chapter (5) Work and energy
1 - Define or explain:
1- Work
2 – Kinetic energy
3 – Potential energy
4 – Power
2 – Complete the space:
1- The work done by a force is positive when F is …………. To s, negative when F is ……………….. to s, and zero when F is …………. To s.
2 – The S.I. unit for work is the ………..
3 – The kinetic energy of an object is a measure of its ability to …………….
4 – The kinetic energy of an object equals it’s ……….. Plus the total work done by ………….
5 - The final kinetic energy of an object equals its ………… plus the total work done by ……………
6 - Forces that can be included in the potential energy are said to be ………
7 – The S.I power unit is ……….

3 - Exercises:\
1- A child pulls a toy car with 10N force at 20o angle to the horizontal. If the car moves a distance of 6 m, how much work does the child do?
2 – a woman pushes horizontally on a chair with a force of 300N. Compute the work she does on the chair if (a) it moves 2m parallel to the force; (b) it moves 1m opposite to the force; (c) it does not move.
3 – A box of mass 10 kg falls straight down a distance of 2 m. How much work is done by gravitational forces?
4 – A car of mass 1300 kg rolls down a hill a distance of 100m. The road is at an angle of 10o to on the car by gravitational forces?
5 – A 1000 kg automobile has a velocity of 40 kmh-1. What is its kinetic energy?
6 – What is the kinetic energy of a 0.25kg stone moving at 10 ms-1
7 – Show that kinetic energy has dimensions of force times distance.