Fundamental Forces

The gravitational force, described systematically by Isaac Newton in the 17th century, acts between all objects having ……….; it causes apples to fall from trees and determines the orbits of the planets around the Sun.

• mass

• volume

The electromagnetic force, given scientific definition by James Clerk Maxwell in the 19th century, is responsible for the ………. of like and the ………. of unlike electric charges; it also explains the chemical behaviour of matter and the properties of light.

• repulsion/attraction

• attraction/repulsion

Gravity acts between all objects of the universe, no matter how far apart they are, and an electromagnetic wave, such as the light from a distant star, travels undiminished through space until it meets some particle that can absorb it. This means the gravitational and electromagnetic forces operate at a(n) ………. range.

• finite

• infinite

An electromagnetic field can be defined as a property of space caused by the ………. of an electric charge, while a gravitational field is the force field that exists in the space ………. every mass or group of masses.

• motion/around

• stationariness/inside

Broadly speaking, we can say a field is...

• a region in which a body can experience a non-contact force.

• a region in which a body can experience a contact force.

Non-contact forces act between two objects that are physically touching each other. Examples of non-contact forces include: magnetic force, electrostatic force and gravitational force.

• True

• False

A magnetic force is experienced by any magnetic material in a magnetic field.

Opposite magnetic poles (N – S or S – N) ………. each other. Like magnetic poles (N – N or S – S) ……… each other.

• repel/attract

• attract/repel

An electrostatic force is experienced by any charged particle in an electric field.

Choose the emoji that accurately represents the way unlike charges interact.

• ❤️

• 🤬

A gravitational force is experienced by any mass in a gravitational field. Masses are attracted towards each other by gravitational force. Mass is a measure of how much matter is in an object while ………. is force that acts on a mass due to gravity. It is measured in ………. whereas mass is measured in kilograms.

Contact forces are forces that act between two objects that are physically touching each other. Examples of contact forces are: reaction force, tension, friction and air resistance.

• True

• False