Forces and Motion

Question 1

What is a resultant force?

Answer 1

The product of all the different forces acting on an object from all directions.

A resultant force will cause an acceleration.

Question 2

What are forces measured in?

Answer 2

Newtons

Question 3

What is one Newton?

Answer 3

The force that causes 1kg to accelerate 1ms-2

Question 4

What are the typical forces acting on an object?

Answer 4

Thrust/compression

Tension

Friction

Weight

Normal/boyance/upthrust

Question 5

When is an object in equilibrium?

Answer 5

When all forces acting on the object are balanced, and the resultant force on the object is equal to zero.

Question 6

In which direction to resisting forces act?

Answer 6

In the opposite direction to motion

Question 7

Why can forces be written as vectors?

Answer 7

Each force has a magnitude and direction, so it can be represented as a vector.

Question 8

What is the equation of motion?

Answer 8

F = ma

Force (N) = mass (kg) x acceleration (ms-2)

Question 9

In which direction does tension act in a rope?

Answer 9

Away from an object.

Question 10

How do you find the magnitude of a force of 3i + 4j?

Answer 10

‘Pythagorise it’ - square 4 and 3 to get 16 and 9, add them to get 25 and square root this.

The magnitude should equal 5

Question 11

When do we consider particles connected?

Answer 11

If they are on the same line, we can consider them as a whole.

If they are connected by a light, inextensible rod, we can consider them as a whole.

Question 12

What happens if particles are connected via a pulley? Can we consider them to be moving as a whole.

Answer 12

If they are connected by a pulley, we cannot look at them as a whole, as they moving in different directions.