# Chapter Test Friction and gravity

## 22 terms

a push or pull

### newton

the SI unit in which the strength of a force is measured in

### net force

the combination of all forces acting on an object

### unbalanced forces

forces that can cause an object to stop moving, start moving or change direction

### balanced forces

equal forces acting on an object in opposite directions

### What do unbalanced forces acting on an object result in ?

Unbalanced forces acting on an object result in a net force and a change of direction to the direction of the larger force

### What do balanced forces acting on an object result in ?

Balanced forces acting on an object do not change the object's motion.

### friction

the force that two surfaces excert on each other when they rub against each other

### static friction

friction that occurs on objects that are not moving

### sliding friction

friction that occurs when two solid surfaces slide over each other

### rolling friction

occurs when an object rolls across a surface

### fluid friction

occurs when a solid object moves through a fluid

### gravity

the force that pulls objects toward each other

### What does the law of universal gravitation state ?

The law of universal gravitaion states that the force of gravity acts between all objects in the universe.

### What affects the gravitational force between objects ?

mass and distance

### mass

a measure of the amount of matter in an object

### weight

the force of gravity on a person or object at the surface of a planet

### free fall

when the only force acting on a falling object is gravity

### Why do objects accelarate toward the center of the Earth?

gravity is unbalanced

### air resistance

a type of fluid friction objects falling through air experience

### terminal velocity

the highest velocity a falling object can achieve

### projectile

an object that is thrown