1) Force is a pull or push

2) Force is the ability to do work or result in physical
change

3) Force= Mass times acceleration (F = ma)

4) A force is that which changes or has a tendency to change
the state of rest or motion of a body.

**Examples:**

For simplicity sake, all forces (interactions) between
objects can be put into two wide categories: contact forces and forces caused
by action-at-a-distance.

**Contact Forces
contain**: buoyant forces, frictional forces, air resistance forces and normal
forces

**Action-at-a-distance
forces contain**: electrostatic, gravitation and magnetic forces.

**Measuring
Force:**

Force is measured utilizing either the International System
of Units (SI) or the English System of Measurements.

**Common
Units of Force**

--->>SI: Newton (N) 1 N = 0.225 lb;

One Newton (N) of force is described as the amount of force
required to accelerate 1 kilogram (kg) of mass at a rate of one meter for every
second squared (m/s2).

1 Newton = 1 kg m/sec2 (A kilogram is the amount of weight
where 1 N of force will accelerate at a rate of 1 m/s2.)

--->>English System: Pound (LB) 1 LB = 4.448 N

In English system of measurements, a slug is actually the
amount of mass that one pound of force will accelerate at 1 ft/s2 and a pound
mass is the amount of mass that one LB of force will accelerate at 32 feet/s2.

**Describing
a Force:**

A force is actually a vector quantity. A vector quantity is
a quantity that has both direction and magnitude. To completely describe the
force performing upon an object, you must describe both its direction and
magnitude. Therefore, 10 Newtons of force is not a whole description of the
force performing on an object.

(Note: What is the difference between scalar and vector
quantities? A vector provides both direction and strength, a scalar quantity
can be explained using only 1 quantity, magnitude. Samples of scalar quantities
are: energy, time and volume because they only symbolize magnitude with no
direction.

**What is the
Difference between Weight and Mass?**

Demonstrated below are two kinds of scales commonly utilized
in the classroom, a spring scale (left) and a simple balance beam scale on the
right.

On earth the spring scale reads 100g with an unfamiliar mass
attached at the base. To balance the scale on the right a 100g mass was also
required.

### What does
applying a Force do?

**Force leads to
acceleration**.

Newton's Second Law says that: the acceleration (a) of an
object is straight proportional to the force (F) applied and inversely
proportional to the object's mass (m).

Meaning that the greater force you apply to an object, the
more the acceleration. And, the greater mass the object has, the lower the
acceleration.

**Newton's 2nd Law can
be written in equation type: F = ma.**

For falling things we can write F=mg where g is
the acceleration because of gravity. The force of gravity is what leads to free
falling objects to speed up. These objects all accelerate at the identical rate
of 9.8 meters/sec^2