Page 142 - York Global Science 6 - Physical Science

An inclined plane, or ramp, changes the direction of the force and means less

force is needed to move an object up or down. Because of this, the work is
done over a longer distance.

Wedge
A wedge makes work easier by making the force on an
object larger because the force is at the tip (small end) of the

wedge. The force works over a smaller area.

Wheel and Axle
Turning the wheel makes a short, powerful movement of

the axle. A short, powerful movement of the axle makes
the wheel move further.

Pulley
A single pulley changes the direction of the force from
lifting to pulling. There is no change to the size of the

force. When two pulleys are used, the force needed to
move an object is halved. However, a longer rope is
needed and it must travel a greater distance.

Screw

A screw changes the direction of the force from a turning
movement (going around in a small circle) to a movement in a
straight line.

Machines do not make more or less work; they change how the
work is done.

• If a machine uses more force, the distance over which the
force works must be less.
• If a machine uses a force over a longer distance, the force is not as strong.

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