# 2.2 friction and gravity

## 39 terms

### the types of surfaces involved and how hard the surfaces are pushed together

two factors that affect the force of friction are

fricare means to
A. to burn
B. to rub
C. to melt

### B

which surface would it be easiest to pull a sled on
A. soccer field
B. ice rink
C. track

### C

which surface is the hardest to pull a sled on
A. soccer field
B. ice rink
C. track

### two solid surfaces slide over each other

sliding friction occurs when

### two objects that are not moving

static friction occurs between

### a solid object moves through a fluid

fluid friction occurs when

### than sliding friction

fluid friction is easier to overcome

### moving something

static friction keeps you from

### slow down

sliding frictions makes an object

### an object rolls across a surface

rolling friction occurs when

### sliding friction

rolling friction is much easier to over come than

### sliding friction, static friction, fluid friction, rolling friction

name four types of friction

### A

what type of friction occurs when u kick a soccer ball down a hill
A. Rolling Friction
B. Sliding Friction
C. Static Friction
D. Fluid Friction

gravity is

define up

define down

### that the force of gravity acts between all objects in the universe that have mass.

universal gravitation states

### smaller objects

you don't realize gravitational pulls from

### strongest

you only observe effects of the ____?____ gravitational forces.

### the matter in an object

mass is the measure of

### the greater the gravitational force

the more mass an object has

### distance

the strength of the gravitational force also depends on the _____?____ between the object's centers.

### the gravitational force decreases

if the distance increases then

### 20

if you way 120 pounds on earth, then you weigh ______ lbs on the moon

if you way 120 lbs on earth then you would way ______ lbs on mars

### it is the force of gravity on a person or object

what does weight have to do with gravity

### the object is in free fall

when the only force on a falling object is gravity

### an unbalanced force that causes an object to accelerate

in free fall the force of gravity is

### 9.8 m/s2

near the Earth's surface acceleration due to gravity is

### fluid friction called air resistance

an object falling through air experience a type of

### greater the air resistance

the greater the surface area of an object the

### 49 m/s

a marble dropping of a building hit the ground in 5 seconds. how fast was it going?

### velocity

air resistance also increases with

### equal to the force of gravity

air resistance increases until it is

### velocity stops increasing

when forces are balanced the

### terminal velicty

the greatest velocity that can be obtained by an object in free fall is called

### a projectile

an object that is thrown is called

### the force of gravty pulls it toward the earth

when a projectile moves horizontally