# Chapter 10/forces and newton's laws of motion

## 20 terms

push or pull

### Newton

the strength of a force is measured in the SI unit

### Net force

the combination of all forces acting on an object

### Unbalanced forces

forces acting on an object result in a new force and cause a change in the object's motion

### Balanced forces

forces acting on an object do not change the object's motion - equal

### friction

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

### sliding friction

occurs when two solid surfaces slide over each other

### static friction

the friction that acts on objects that are not moving

### rolling friction

when an object rolls across a surface

### fluid friction

occurs when a solid object moves through a fluid

### gravity

a force that pulls objects towards each other

### 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 object is gravity

### air resistance

objects falling through air experience a type of fluid friction

### terminal velocity

the greatest velocity a falling object reaches

### projectile

an object that is thrown

### momentum

a characteristic of a moving object that is related to the mass and velocity of an object

### inertia

the tendency of an object to resist a change in motion

### Law of conservation of momentum

in an absence of outside forces the total momentum of objects that interact does not change the amount of momentum is the same before and after they interact