Questions from pages 80 (1-5), 81 (1-4), 82 (1-5)

Page 80,

1.
a. Work is using a force to move an object, work = force x distance.
b. A machine is a mechanical device that handles work. A machine is something that makes easier to do.
2. The answers A (pushing a mower), B ( Cleaning your teeth) and C (Cycling) are all work as, you are moving a mower, moving your tooth brush, and peddling your bike respectively.
3. To keep on working, you need energy from chemicals like glucose, to keep on producing force.
4. Spanners, pliers, and can openers, are considered machines, because they make work easier.
5. Tweezers, Cart, and slingshot.

Page 81

1. Pulley wheels and a rope.
2. A pulley system can help a mechanic out, by lifting the car engine up and carrying it across to a car or other area.
3.
a. A chain is used to transfer the force of the peddles and crank shaft to the wheels.
b. The Gears are needed to turn the wheel using the force transmitted by the chains.
4.Cycling in high gear is when a turn of the crank shaft makes many turns of the wheel, while low gear is about a ratio of 1 crankshaft turn: 1 or 2 wheel turns.

Page 82

1.
a.Wedges
b.Rollers
c. Ramps
2.
a.By placing them on a flat surface.
b. The crane
4. Wedges are used for putting feet into tight shoes, and ramps are used to move wheelchair people to move up higher.
5. 140m x 25,000 N = 350,000 J

NUMBER 3