Work and Machines worksheet

13.4 Pg 80

1a) What is work? using a force to move an object
1b) A Machine: Anything which makes it easier to do work

2a) Pushing a Mower: Yes because you use the 'push' force to move the mower.
2b) Cleaning your teeth: Yes because you are using the 'push' force to move the brush around your teeth
2c) Cycling: Yes because you're moving your legs with the pedals and arms when you steer the bicycle.
2d) Reading: No because you're not using a force.

3) Why you need food for using force: Energy to keep your body functioning.

4) How to simple machines help: They help unscrewing nuts, opening cans, cutting wire and lifting cars which are things we would use a lot of energy on but with these machines we only need to use a little force.

5) other simple machines: Wheel/Axle, Nail, Carjack.

Pg. 81: 1-4

1) You need a set of pulley wheels and a rope for a pulley system
2) How does the pulley system easily lift the car engine: Because the pulley system divides the work into seperate ropes so each rope lifts a 100N. Another reason is because now there is a smaller force needed because of the greater distance.

3a) The chain: The chain is used as a rope like that of a pulley, you put the force on the chain it transmits the force to the wheels.

3b) The cycle's gears change the number of times that one turn of the crankshaft turns the back wheels.

4) Low gear helps you climb high places because the crank turns the back wheel once or twice which is enough to keep going up hill.

82 1-5: (TO BE COMPLETED)