Simple Machines

Work and machines

1- What is meant by doing:
a- Work: Is using a force to move an object.
b- Machines: Is anything which makes work easier to do.

2-Are you doing work when you are:
a-Pushing a Mower: Yes because you are transferring energy from one object to another.
b-cleaning your teeth: Yes because you are transferring energy from your arm to the brush while you move it up and down.
c- Cycling: Yes because you are moving your legs in a circular motion to transfer your energy from your body to the bike.

3-Why must you eat if you are doing work?
Work is transferring your energy from your body to the certain object. Because Work consumes energy, you will need a replacement for it and so food can be made into energy after being digested and through your intestines to merge with your blood and become energy.

4- Why are spanners, pliers, and can openers called machines?
Since machines are any device or anything that makes work easier, the following objects do make work easier. For example, it is easier to use can opener rather than smashing it or opening it with your hands.

5- Give other names of simple machines.
Knife, scissors, cutter and screw drive.

Pulleys, gears and other wheels

1- What do you need to make a pulley system?
To make a pulley, it is required to have two wheels and a rope, a hooker to hang it from up on a ceiling or anything equivalent.

2-two examples of why it is easier to lift an engine with a pulley.
first reason is when he pulls the pulley down, it is easier to pull down rather than lifting it up to your chest
second reason is when you pull down, you are using your weight as well rather than your arm force only. This way the weight or pressure distribute on some parts of your body and will give you a boost for your force.

3- What is the job of:
a) the chain:The chain's job is transfer the power that is generated by your legs moving the peddles to the wheels in the bike.
b) The gears on a bicycle: The cycle's gear changes the number of times that one turn of the crankshaft turns the back wheel

4-What is the difference between the cycle in high gear and low gear?
In high gear, the chain runs over a small cog wheel where it reduces the speed however, it increases the amount of turns and decreases the force you have to do. It is used for low roads, or in streets. In low gear, the chain uses the bigger cog wheel where it decreases the amount of turns and increases the force you have to do and increases your speed. It is used in high roads, mountains or simply when you need to speed up.

5- Other uses of pulleys??

Pulleys can be used to lift heavy weights to to the top. For example if you were trying to lift up an air-conditioner to the roof, you might think of using the pulley to ease your work. Pulleys are also used in theater where it is hooked to the curtains as well as our houses.

Building a pyramid