FORCES AND MACHINES

If you apply sufficient force to a rigid ogject,it will...

• break

• change shape temporaly

• change shape permanenly

If a ball is rolling on the grass, it will slow down and stop because of...

• a water resistance

• speed

• friction

A car travels 300km in 6 h. Its speed is...

• 20km/h

• 50km/h

• 180km/h

You throw a ball up in the air .As it travels upwards, gravity..

• causes the ball to speed up

• causes the ball to slow down

• does not affect the ball

The component of a machine that produces movement is the

• operating part

• structure

• motor

Indicators and screens

• give information about what the machine is doing

• receive information from outside the machine

• distribute electricity throughout the machine.

Gears are

• levels that turn in circles

• wheels with teeth

• rods that support rotating wheels

Pedals on a bicycles

• axles

• belts

• levers

Contact forces include:

• Muscular force and gravity

• Gravity and friction

• Gravity and speed

• Muscular force and friction

In a permanent change...

• When we remove the force, the object returns to its initial shape.

• When we remove the force, the object doesn't return to its initial shape.

• The object doesn't change shape