Forces in Action

Question 1

What are the four fundamental forces?

Answer 1

• Gravity
• The Electromagnetic Force
• The Weak Interaction
• The Strong Interaction

Question 2

What is the Normal Reaction/Contact Force?

Answer 2

The force that acts perpendicular to the point of contact of a body and the surface with which it is in contact.

Question 3

What is Upthrust?

Answer 3

The upwards force that a liquid or gas exerts on a body floating in it due to the water displaced.

Question 4

What is Friction?

Answer 4

The force caused by the interatomic and intermolecular forces when two surfaces are in contact.

Question 5

What is Terminal Velocity?

Answer 5

The velocity at which an object’s drag equals its accelerating force. Therefore there is no resultant force and zero acceleration.

Question 6

What does it mean when objects are in equilibrium?

Answer 6

It means that all of the forces acting on them in the same plane are balanced meaning there is no resultant force. This means an object will either be stationary or travelling at a constant velocity.

Question 7

What is the Moment of a Force?

Answer 7

The product of a force and the perpendicular distance of its line of action from the point or axis.

Question 8

What is the Principle of Moments?

Answer 8

For an object to be in rotational equilibrium, the sum of the clockwise moments must equal the sum of the anticlockwise moments.

Question 9

What is a Couple?

Answer 9

Two forces that are equal and opposite to each other but not in the same straight line.

Question 10

State Archimedes’ Principle

Answer 10

The upward buoyant force (upthrust) exerted on an object immersed in a fluid whether fully or partially submerged is equal to the weight of the fluid that the object displaces.