(P2)Forces and their Effects

Question 1

What is work done and how is it calculated?

Answer 1

The amount of energy transferred (joules)

Work done = force x distance moved in direction of force

Question 2

What is power and how is it calculated?

Answer 2

The rate of how fast energy is transferred (watts)

Power = work done / time

Question 3

Name the three non-contact forces

Answer 3

Gravity, magnetism and electrostatic charges

Question 4

What does it mean if a body has a resultant force of 0?

Answer 4

It is either stationary or moving at a constant speed

Question 5

What is a moment?

How do you calculate it?

Answer 5

When a force which acts at a distance from a pivot (point at which object rotates) causes a turning effect (Nm)
Moment = force x distance to direction of force

Question 6

What is the principle of moments?

Answer 6

Sum of clockwise moments = sum of anti-clockwise moments

Question 7

A lever can be used to cause rotation. The nature of this rotation depends on:

Answer 7

The input force (force provided by user of lever), the output force (force that results from input force) and the fulcrum (turning point at which both forces act)

Question 8

How is a high gear created?

Answer 8

When a large input gear turns a smaller output gear. This leads to a high speed and low turning effect/moment

Question 9

How is a low gear created?

Answer 9

When a smaller input gear turns a larger output gear. This leads to a low speed and a high turning effect/moment

Question 10

What do gears and levers have in common?

Answer 10

They both transmit the rotational effect of a force and both alter the size of the output force