Wheels and Lever

What is a gear ?

• a wheel with a grooved rim used to raise heavy weights

• a rigid bar resting on a pivot used to help move a heavy load

• a set of tooth wheel that work together to transfer a force

• the point on which a lever rests

What is pulley ?

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What is this ?

Who can help us pull some heavy thing up ?

What is this ?

• friction

• pulley

• lever

• I don't know

What is simple machines ?