Types of - [Contact Force, Non-Contact Force (s)] - Examples

We are explaining the interaction between bodies. In this brief article, you'll discover all you need to know about contact force (s), types of contact force with examples, non-contact force (s), and examples. Let's start discussing one by one.

Must Read: What is Force with Examples?

Contact Force (s)

The forces which act on bodies when they are in physical contact. These forces are produced and experienced when a body comes in contact with another body. For example,

• The force of friction (frictional force)
• Normal reaction force
• Force of tension exerted by a string
• Force exerted by a spring
• Force exerted on two bodies during collision etc.

When you pushed on an object you are definitely contacting the object directly or indirectly.

Types of Contact Forces

Frictional Force: When a body slide (or rolls) over a rough surface, a force starts acting on the body in a direction opposite to the motion of the body, along with the surface in contact. This is called the frictional force or the force of friction.

Normal reaction force: When a body is placed on a surface, the body exerts a force downwards equal to its weight on the surface, but the body does not move (or fall) because the surface exerts an equal and opposite force on the body normal(90⁰) to the surface which is called the normal reaction force.

Tension force: When a body is suspended by a string, the body, due to its weight W pulls the string vertically downwards and the string in its stretched condition pulls the body upwards by a force which balances the weight of the body. This force developed in the string is called the tension force T (or the force of tension).

Force exerted by a spring:  If the spring is compressed, it pushes attached object away with a force F so as to come back to its original form.The force F acting on the object to pull it away is called the restoring force.

Force exerted during collision: When two bodies collide, they push each other. As a result, equal and opposite forces act on each body.

Contact Force Examples

Suppose that you're thirsty and there is a glass full of water lying on the table. In order to drink some water from this glass, you have to lift the glass towards your mouth. That is you have to apply force on the glass.

How are you applying this force? - You are touching the glass and lifting it in your hand. So, the force you are applying on the glass is a contact force.

• When a book placed on the table top is pushed to the right, the force of friction acts on the book towards the left. This force resists the motion of book on the table top.
• When you hold a block on your palm, the block exerts a force due to its weight downwards on your palm. You have to exert a reaction force upwards on the block normal (90⁰) to the palm to keep the block in position.
• When you kick a soccer ball you are contacting the soccer ball during the kick. So, it is also a contact force.

Non-Contact Force (s)

The forces experienced by bodies even without being physically touched are called the non-contact forces or the forces at a distance.

• The gravitational force,
• Electrostatic force, and
• Magnetic force are the non-contact forces.

Non-contact forces do not require contact to cause a force. They have an invisible force field or field of influence.

Gravitational force: In-universe, each particle attracts the other particle due to its mass. This force of attraction between them is called the gravitational force.

Electrostatic force: Two like charges repel, while two, unlike charges, attract each other. The force between the charges is called the electrostatic force.

Magnetic force: Two like magnetic poles repel, while two, unlike magnetic poles, attract each other. The force between the magnetic poles is called the magnetic force.

Non-Contact Force Examples

Gravitational force

• If a body is thrown up in the air, it goes up, reaches a height and then returns to the ground.
• A coin falls down when it is dropped from a height.

Electrostatic force

• When a comb is rubbed on dry hairs, it gets charged. If this comb is brought near the small bits of paper, opposite charges are induced on the bits of paper and they begin to move towards the comb. The motion of paper bits is due to the attractive electrostatic force exerted between the unlike charges on the paper bits and the comb.

Magnetic force

• When a pole of a magnet is brought near a small iron nail (without touching it), an opposite polarity is induced on the nail and it moves towards the magnet.

This is all about the basics of contact force (s), types of contact force with examples, non-contact force (s), and examples.