# How is Force Measured

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.