P2.3 - Motion and pressure

Question 1

What is the equation for speed?

Answer 1

speed (m/s) = distance travelled (m) / time taken (s)

Question 2

What is the difference between average speed and instantaneous speed?

Answer 2

Average speed is the speed of the entire trip while the instantaneous speed is the speed of something at a specific time.

Question 3

What is relative motion?

Calculate the relative motion of two cars moving towards each other at 30 mph each.

Answer 3

Relative motion is how fast one thing is travelling compared to another.
30 mph + 30 mph = 60 mph
If one of the cars looks at the other they would see the other cat travelling at 60 mph.

Question 4

How do you calculate pressure?

Answer 4

Pressure=force/area

Question 5

Which directions is gas pressure exerted in?

Answer 5

Pressure is exerted in all directions.

Question 6

What is the meaning of incompressible? Explain why liquids are incompressible.

Answer 6

Incompressible - cannot be compressed
Liquids are incompressible because there is very little space between the particles unlike gases. This is why liquids pass on any pressure applied to them.

Question 7

Explain what is upthrust and how it happens.

Answer 7

Upthrust is the force that keeps things afloat. There are more water molecules pushing the bottom of an object up than air molecules pushing it down.

Question 8

Which direction does pressure act in?

Answer 8

It acts in a direction that is at 90°, or normal to the surface.

Question 9

How do you calculate pressure?

Answer 9

pressure (N/m²) = force (N) / area (m²)

Question 10

What should you be careful of when calculating pressure?

Answer 10

The area might be measured in cm instead of m.

Question 11

What is moment and what is it measured in?

Answer 11

Moment is the effect of a turning force on a pivot. It is measured in Nm (Newton meters).

Question 12

How do you calculate moment?

Answer 12

moment (Nm) = force (N) x distance from the pivot (m)

Question 13

Calculate the clockwise moment (the seesaw turning clockwise around the pivot) of a seesaw is someone sits 0.5 meters from the pivot and exerts a force of 1000 newtons. Key data:
0.5 m
1000 N

Answer 13

clockwise moment = force x distance from the pivot
= 1000 N x 0.5 m
= 500 Nm

Question 13

Calculate the clockwise moment (the seesaw turning clockwise around the pivot) of a seesaw is someone sits 0.5 meters from the pivot and exerts a force of 1000 newtons. Key data:
0.5 m
1000 N

Answer 13

clockwise moment = force x distance from the pivot
­­­ = 1000 N x 0.5 m
= 500 Nm