Pg. 81 Answers

1. Ropes and pulley wheels are needed when doing a pulley system.
2. Some of the reasons that the mechanic will find the pulley a good machine to help left the car engine since he will be using less force to pull up the car engine . Another reason is that it is easier to left the car engine because it is supported by the ropes and the wight of the person pulling it.
3. The chain runs over the small / large cog wheel at the back so that one turn of the crank turn the back wheel. The cycle's gear changes the number of times that one turn of crankshaft turns the back wheel.
4. The difference between low gear and high gear is that the low gear you ride with it when climbing a hill and the with every paddle the back wheel moves one than once while the high gear is when you ride with it