Forces

Question 1

What is a force?

Answer 1

A force is an influence that causes an object to change. Gravity is an example of a force. Pushes and pulls are examples of forces but they are not the only ones.

Question 2

Which force did Charles-Augustin de Coulomb first describe?

Answer 2

Charles-Augustin de Coulomb first described the electrostatic force. Isaac Newton first described gravity.

Question 3

What does Newton’s First Law of Motion state?

Answer 3

Newton’s First Law states that objects with balanced forces acting on them will stay at rest or in constant motion. F = ma is an equation which summarises Newton’s Second Law.

Question 4

What are the units of force?

Answer 4

The units of all forces are newtons. A bag of sugar has a gravitational force (weight) of 10 newtons.

Question 5

Newton’s Second Law of Motion can be summarised by which equation?

Answer 5

Newton’s Second Law of Motion can be summarised as F = ma. It relates to unbalanced forces

Question 6

What is friction?

Answer 6

Friction is a force that opposes motion. It acts when two or more surfaces slide past each other.

Question 7

How do you calculate resultant force?

Answer 7

The resultant force is calculated by adding together all the forces that act upon an object. Dividing these forces will not give you a useful value.

Question 8

What happens if the resultant force on a car is in the direction in which it is travelling?

Answer 8

If the resultant force on a car is in the same direction as the car is travelling it will speed up.

Question 9

What is the gravitational field strength of the Moon?

Answer 9

The gravitational field strength of the Moon is 1.6 N/kg. 10 N/kg is the gravitational field strength of Earth.

Question 10

If a person has a weight of 600 N, how much will they weigh on the Moon?

Answer 10

Weight is mass multiplied by gravitational field strength. A weight of 600 N is equivalent to a mass of 60 kg. So 60 kg x 1.6 N/kg is 96 newtons (N). 600 N is their weight on Earth