A simple machine has __________ parts, but a complex machine is made of many parts.
only one or a few
Are the machines in the picture simple or complex?
They are simple machines.
__________ can make an object start moving, stop moving, change shape or break.
Forces
Some objects, like a sponge, change shape __________. They return to their original shape when the force stops acting on them.
temporarily
Some objects, like clay, change shape __________ when a force is applied to them. They keep their new shape.
permanently
Some objects break when a lot of force is applied to them. These are __________ objects.
rigid
__________ is a force that pulls objects down towards Earth. We see the effct of this force when an apple falls from a tree.
Gravity
___________ is a force that attracts some metals. It flows from the north pole to the south pole.
Magnetism
__________ is a force that occurs when two objects rub against each other. It slows down moving objects.
Friction
Some forces can act on an object at a distance. These are called __________. For example: gravity and magnetism.
non-contact forces
A magnet has two __________, north and south.
poles
The opposite poles of two magnets __________ each other.
attract
The same poles of two magnets __________ each other.
repel
The fixed point in a lever is called a __________ or a __________.
fulcrum, pivot point
A __________ is a simple machine that turns on a fixed point and makes it easier to lift heavy objects.
lever
An __________ is a ramp that we use to move objects up and down. It reduces the force we need to push an object.
inclined plane
