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SITEMAP   School-college Physics Notes: Forces Section 1.1 What is a force?

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Forces 1: 1.1 What is a force?

Contact and non-contact forces

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INDEX of my physics notes on FORCES Section 1. An introduction

1.1a What is a force?

The first thing to say is you can't see a force!

BUT, you can observe its effect and often quantify it with equations.

The unit of force is the newton (N) and there are all sorts of forces e.g.

A force is a 'mechanical' push or pull effect, acting on an object when it interacts with something.

You can have forces of repulsion and attraction or from friction of materials rubbing against each other etc.

The result of the interaction depends on the nature and magnitude of the forces involved.

The value of force can be very small or very large, from zero to an 'immeasurable' value at the centre of a black hole!

You are familiar with the results of electrical, magnetic or gravitational forces and mechanical forces such those acting in the spring of a clock, the engine of a road vehicle or the motion of planets.

You also will learn formulae to do calculations on gravity and acceleration.

Arrows are used on diagrams to show the direction and magnitude of a force - but first check out you know the difference between scalar and vector quantities explained in section 1.2.

1.1b Comparing contact forces and non-contact forces

Forces between objects can be divided into two main categories.

The interactive forces involved when two objects are in physical contact - contact forces.

The interactive forces when the two objects are apart, non-contact forces, described as 'action at a distance force'.

Sometimes non-contact forces are acting between objects that are actually in contact e.g. you sitting in front of your computer is an example!

This involves gravity (non-contact) and weight and compression (contact forces).

See the flask standing on a bench example later parts of section1. on forces.

INDEX of my physics notes on FORCES Section 1. An introduction

Keywords, phrases and learning objectives for forces

Be able to explain what a force is and what can a force do?

Know the unit of force is a newton, N

In the interaction of objects with each other, know the difference between contact forces and non-contact forces


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INDEX of my physics notes on FORCES Section 1. An introduction