ForceTypes

1

Definition of Force

Drawing the Force

Dimensions and Units of Force

Tension

Elastic Force

Gravity

Normal Force

Friction

Drag

Pulleys

ForceTypes

2

Force

That which causes a particle to accelerate.It is a vector!

Knight’s Definition

A force …

is a push or a pull on an object.It is a vector. It has both magnitude and direction.It requires an agent. Something does the pushing or pulling.It is either a contact force or a long-range force (gravity).

ForceTypes

3

Force, like any vector is drawn as an arrow with the symbol or magnitude and units.

The tail of the force is placed on the part of the object that is experiencing the force.

In a free-body diagram, the tail is placed on the point representing the particle.

The direction of the force and its magnitude are determined by the type of force it is.

ForceTypes

4

Force

The SI unit of force is the Newton (abbreviated as N).

One Newton is the same as one kilogram-meter per second squared.

Another unit of force is the pound.

ForceTypes

5

Tension

The magnitude of the tension is the same everywhere in the rope.

T

T

ForceTypes

6

Name of Force

Symbol

When does this force occur?

Where does this force occur?

Associated Energy

Tension

If an object that is experiencing the force is pulling but not stretching another object

On the object that is experiencing the force at the point where the pulling occurs

No associated energy

T

ForceTypes

7

Spring Force

xk

spF

ForceTypes

8

Name of Force

Symbol

When does this force occur?

Where does this force occur?

Associated Energy

Spring Force

On the object experiencing the force where it connects to the object that stretches/compresses

Elastic Potential Energy

If an object that is experiencing the force is stretching (or compressing) another object

springF

ForceTypes

9

Gravity

GF

GF

r

1m

2m

ForceTypes

10

Name of Force

Symbol

When does this force occur?

Where does this force occur?

Associated Energy

Gravity

or

At the center-of-mass of the object receiving the force

Gravitational Potential Energy

If there are two massive objects present

GF

w

ForceTypes

11

Normal Force

m

N

m

N

w

ForceTypes

12

Name of Force

Symbol

When does this force occur?

Where does this force occur?

Associated Energy

Normal Force

or

If an object touches the surface of another object

On the object receiving the force at the point(s) where it touches the surface

No associated energy

NFn

, N

ForceTypes

13

Friction

m

N

f

Direction of motion

or possible motion m

N

f

Direction of motion

or possible motion

ForceTypes

14

Name of Force

Symbol

When does this force occur?

Where does this force occur?

Associated Energy

Friction

or

If an object touches the surface of another object

On the object receiving the force at the point(s) where it touches the surface

Thermal Energy

sf

kf

ForceTypes

15

Drag

D

ForceTypes

16

Name of Force

Symbol

When does this force occur?

Where does this force occur?

Associated Energy

Drag

If an object is moving through a liquid or gas.

On the object receiving the force at the point(s) where it touches the liquid or gas

Thermal Energy

D

ForceTypes

17

Pulleys

Pulleys simply change the DIRECTION of a force.

T

T