Page 86 - York Global Science 6 - Physical Science

Think!

What forces do you know?
What forces are acting on the toy car?

Complete the diagram in the Workbook
to show the forces.

Forces always act in pairs.

This box is not moving.
The two forces acting on it are

equal.

The force of gravity is equal to the
upward force (the reaction force)
of the table.

Forces that are equal in size but

opposite in direction are called
balanced forces.

Balanced forces do not change
the motion of an object. An object that is stationary (at rest) is an example

of balanced forces. An object that is moving at a steady speed in the same
direction is also an example of balanced forces.

The forces are unbalanced when a change in speed or direction happens.

When the motion of an object changes, there are still forces working in
opposite directions, but the forces are unbalanced.
If you need to move something, or change the direction of movement, you

need the forces to be unbalanced.

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