# chapter 2-3

## 30 terms

A push or pull.

### newton

The strength of a force is measured in the SI unit.

### netforce

the combination of all forces acting on an object.

### unbalanced forces

A net force acting on an object can make it unbalanced.

### balanced forces

equal forces acting on an object in opposite directions.

### friction

the force that two surfaces exert each other when they rub together.

### static friction

friction that acts on objects that are not moving.

### sliding friction

friction that occurs when one solid surface slides over another.

### rolling friction

friction that occurs when an object rolls over a surface.

### fluid friction

friction that occurs as an object moves through a fluid.

### gravity

the force of attraction between all masses in the universe.

### 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 the planet.

### free fall

the motion of a falling object when the only force acting on it is gravity.

### air resistance

objects falling through air experiance a type of fluid friction.

### terminal velocity

the force of air resistence equals the weight of the object.

### projectile

an object that is thrown

### inertia

the tendency of an object to resist any change in its motion

### momentum

a moving object that is to the mass and the velocity of the object.

### Law of conservation of momentum

The rule that in the absence of outside forces the total momentum of objects that interact does not change.

### satellite

any celestial body orbiting around a planet or star

### centripetal force

any force that causes an object to move in a circular path.

### pressure

the force exerted on a surface divided by thue total area which the force is exerted.

### pascal

a unit of pressure equal to one newton per square meter.

### fluid

A material that can easily flow.

### barometer

an instrument that measures atmospheric pressure.

### buoyant force

upward force exerted on an object immersed in a fluid.

### Archimedes principle

the buoyant force on an object is equal to the weight of the fluid displaced by the object.

### density

the amount per unit size.

### pascals principle

When force is applied to fonfined fliud, the change in pressure is transmitted equally to all parts of the fluid.