Force and Types of Forces | Mass vs Weight

1. Gravitational force – this is the force of attraction between two bodies of given masses.
- Earth's gravitational force is the force which pulls a body towards its center. This pull of gravity is called weight.
2. Force of friction – this is a force which opposes the relative motion of two surfaces in contact with each other. Friction in fluids is known as viscosity.
3. Tension force – this is the pull or compression of a string or spring at both its ends.
4. Upthrust force – this is the upward force acting on an object immersed in a fluid.
5. Cohesive and adhesive forces – cohesive is the force of attraction of molecules of the same kind while adhesive is the force of attraction of molecules of different kinds.
6. Magnetic force – this is a force which causes attraction or repulsion in a magnet.
7. Electrostatic force – this is the force of attraction or repulsion of static charges.
8. Centripetal force – this is a force which constrains a body to move in a circular orbit or path.
9. Surface tension – this is the force which causes the surface of a liquid to behave like a stretched skin. This force is cohesive.

Factors affecting surface tension

a) Impurities – they reduce the surface tension of a liquid i.e. addition of detergent.
b) Temperature – rise in temperature reduces tension by weakening intermolecular forces.

Mass is the amount of matter contained in a substance while weight is the pull of gravity on an object.
The SI unit for mass is the Kg while weight is the newton (N). Mass is constant regardless of place while weight changes with place.
Weight = Mass x g, where g is the gravitational force

Differences Between Mass and Weight Mass

1. Mass

It is the quantity of matter in a body
It is measured in kilograms
It is the same everywhere
It is measured using a beam balance
Has magnitude only Weight

2. Weight

It is the pull of gravity on a body
It is measured in Newtons
It changes from place to place
Measured using a spring balance
Has both magnitude and direction

Measuring Force

A spring balance is the most common tool for measuring force.

A scalar quantity is a quantity which has magnitude (size) only . Examples are distance, mass, speed

A vector quantity is a quantity which has both magnitude and direction. Examples are displacement, weight, velocity