Page 80

1.

a. Work is using any type of force to move something.

b. A machine is a mechanical device that handles work. They make it easier to do the work.

2. The answers A , B and C all work because in each action you are moving something by using a force. In D, you're not doing work because you dont use a type of force to read.


3. Because food gives you energy, and you need energy to be able to handle work.

4. Spanners, pliers, and can openers, are called machines because they make work easier.

5. scissors and hammers.

pg 81

1. Pulleys wheels and a rope.

2. you can lift the engine up by pulling down on the rope which is far more easier than a human picking a car up. Also a pulley supports the car equally.

3.

a. The chain passes on the force to the back wheels, turning them.

b. The cycle gears change the number of times that one turn of the crankshaft turns the back wheels.

4. The different gears have different amounts of forces. The higher gear can be used in flat surfaces because there is enough force to make the wheels spin. if you were going up a hill you need to shift it to low gear because the high gear doesnt have enough amount of force to make the wheels spin up a hill.