FORCE
A spring balance can be used to measure small forces. It consists of a coiled spring fixed to the other end with a hook at the other end. The body upon which the force acts is attached to the hook. The distance through which the spring is stretched is directly proportional to the force applied by the balance.
- Fundamental forces
- Non fundamental forces
- The force of gravity
- The electromagnetic force
- The strong nuclear force
- The weak nucleus force
The force of gravity is the pull by which the earth, moon and other very large bodies attract other objects towards themselves. It is commonly referred to as the weight of the object that is attracted.
In mechanics, a freely falling body in the air moves down irrespective of its mass. This is due to force of gravity.
Example 1
Where acceleration due to gravity on the earth, g = 9.8m/s2
It pulls (attracts) objects towards the centre of the earth.
It is directly proportional to the mass of the object. This means that the greater the mass the greater the pull of gravity.
It is strong when the mass is closer to the centre of the earth.
It should be noted that the weight of an object is directly related to its Mass.
It is the gravitation’s field strength (10N/Kg)
It is the acceleration of free fall (10m/s2
Examples where electromagnetic forces are involved include:
In the formation of molecules of a substance. Atoms attract each other to form molecules. This is due to electromagnetic force.
In two parallel wires carrying current. If places near each other, the electromagnetic force acts on the wires.
The following are the properties of gravitational force
It always attracts objects.
It is the weakest force among the four basic forces.
It is a central force (gravitational force between two objects acts along the line joining the centres of the objects.
It operates over very long distance.
Properties of electromagnetic force include
It may be attractive or repulsive is nature
It is a central force
It is stronger than gravitational force
It is also a long-range force (operates over a very long distance)
It is basically an attractive force
It is a non-central force (does not act at the centre)
It is stronger than gravitational force
It is a short-range force that is it operates only up to distance of the order of 10-14m
It is much stronger than the gravitational force but weaker than the strong nuclear force and electromagnetic force
It acts on small ranges of up to 10-17m
CLASS ACTIVITY
Define the term force and give its SI unit.
Mention four fundamental types of force that you know.
Define the following terms: Force of gravity; Strong nuclear force; Electromagnetic force.
A body has a mass of 40kg. Find its weight.
If the resultant force acting on an object is ZERO then:
The object will remain stationary if it was stationary when the resultant force became zero.
Move at a constant (steady) speed in a straight line if it was moving when the resultant force became zero.
The object will accelerate or decelerate (speed up or slow down).
