Forces
To make an object move a ___________ must be applied to it.
Force
___________ are machines with few or no moving parts.
simple machines
People use _______things to reduce friction.
slippery
This type of force can attract or repel each other.
magnetism
You can not see _____, but it is what keeps you on Earth.
Gravity
A force is a _________ or a _________.
Push or a Pull
This simple machine has a flat, slanted surface. For example, a ramp.
inclined plane
People use ______ surfaces or sticky things to increase friction.
rough
Magnets can attract things made of ___________.
Iron
Gravity is a ______________ force between two objects, such as you and Earth.
pulling
_____ happens between objects that touch. Think about a baseball game. A bat must touch a ball to change its direction.
Contact Forces
A ___________ is a straight bar that moves on a fixed point. For example, a seesaw.
lever
The __________ is the fixed point on a lever.
fulcrum
Mention three things that magnets cannot attract.
How much gravity does it take to keep you on Earth?
your weight
Some forces like _________ and ________ can act on an object without touching it.
magnetism and gravity
This simple machine uses a rope and a wheel to lift an object. For example, it make the work easier when you pull a bucket of water down and up a well.
pulley
If you put two inclined planes back to back, you get a __________. This simple machine allows you to split objects apart. For example, a knife.
wedge
Magnets can attract or repel objects through _______, liquids, or _________.
solids, gases
The more ________ an object has, the more gravity pulls on it.
mass
In what ways can a motion be changed by a force?
Motion can change in speed or direction.
This simple machine moves around a post. For example, the Ferris wheel or a bike.
wheel and axle
A _______________ is two or more simple machines put together.
compound machine
The force that occurs when one object rubs against another object is called ________________.
Friction
The force of gravity can also pull objects from a _______________.
distance