Physics - Motion & Pressure

Question 1

What is speed?

Answer 1

The measure of how far something travels in a particular time

Question 2

How do you calculate speed?

Answer 2

distance travelled (m)
------------------------------
time taken (s)

Question 3

What is instantaneous speed?

Answer 3

The speed of an object at a particular moment in time

Question 4

How do you work out average speed?

Answer 4

total time

Question 5

What is relative motion?

Answer 5

How fast one object is travelling compared to another

Question 6

What is the relative speed of two objects moving at the same speed in the same direction?

Answer 6

zero

Question 7

What is the relative speed of two cars moving at 30mph towards each other?

Answer 7

60mph

Question 8

What does a distance-time graph show?

Answer 8

The distance that an object travels over a certain time

Question 9

What does a steep line show you?

Answer 9

The object is moving fast

Question 10

What produces gas pressure?

Answer 10

The amount of collisions between the air molecules and their container

Question 11

How can you increase pressure?

Answer 11

By squashing a gas into a smaller volume, which causes more collisions

Question 12

What makes the size of a balloon increase?

Answer 12

When there are more collisions in the inside than the outside

Question 13

What happens when the temperature of a gas decreases?

Answer 13

Its molecules move slower and fewer collisions occur with the sides of the container

Question 14

What happens to the pressure of a solid container when the gas pressure decreases?

Answer 14

It decreases

Question 15

What do the molecules do when the temperature of a gas increases?

Answer 15

They collide more and are much faster

Question 16

What happens when more gas is added to a container?

Answer 16

The gas inside becomes compressed

Question 17

What happens when a gas is compressed?

Answer 17

As more molecules are added in the same space, more collisions occur

Question 18

Why is a stronger container needed to hold a compressed gas?

Answer 18

The pressure is bigger, so the force exerted by the gas over the area of the container is bigger

Question 19

What is atmospheric pressure?

Answer 19

The pressure that the air around you exerts

Question 20

Why is the atmospheric pressure at sea level higher than at a mountain?

Answer 20

Gravity pulls the air particles towards the Earth, and because they are closer more collisions occur, increasing the pressure

Question 21

Why does gas have a higher density at sea level?

Answer 21

There is more mass of gas in a certain volume

Question 22

What are oxygen tanks?

Answer 22

Tanks that contain oxygen gas compressed into a small volume

Question 23

What happens when liquid pressure occurs?

Answer 23

Water molecules push on each other and on surfaces in all directions

Question 24

Why are liquids incompressible?

Answer 24

Because the liquid particles are touching each other with very little space between them and pass on any pressure

Question 25

Why are gases compressible?

Answer 25

There is lots of space between the gas particles

Question 26

What does pressure at a certain depth depend on?

Answer 26

The weight of the water above it

Question 27

What causes upthrust and what does it do?

Answer 27

Upthrust is caused by liquid pressure and acts on any object that is floating, or is submerged in a liquid

Question 28

Why does a rubber duck float and what is produced?

Answer 28

More water molecules hit the bottom of the rubber duck than there are air molecules hitting the top, which produces upthrust

Question 29

When would an object not be able to float?

Answer 29

If the area in contact with the water is too small, there is not enough upthrust to balance its weight so it sinks

Question 30

What force is required to push a submarine up and how is it produced?

Answer 30

Upthrust is produced as underwater there is a difference in pressure between the top and bottom of the submarine

Question 31

What is pressure?

Answer 31

A measure of how much force is applied over a certain area

Question 32

What direction does pressure act in?

Answer 32

90°, or normal, to the surface

Question 33

How do you calculate pressure?

Answer 33

force (N) ---------------------- area (m^2)

Question 34

Why do the studs on the bottom of a football boot have a smaller area compared with the area of the foot?

Answer 34

In order to produce a bigger pressure, which makes the studs sink into the ground and move quicker as well as stronger grip

Question 35

Why do snowshoes require a big area?

Answer 35

It lessens the pressure on snow so that you do not sink

Question 36

What does a turning force's distance depend on?

Answer 36

A pivot

Question 37

What is the turning effect of a force and what does it depend on?

Answer 37

A moment, which depends on the force being applied and how far away it is from the pivot

Question 38

How do you calculate a moment?

Answer 38

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

Question 39

How does the moment of your weight act?

Answer 39

Anticlockwise

Question 40

What is the law of moments?

Answer 40

When an object is in equalibrium the sum of the clockwise moments is equal to the sum of the anticlockwise moments

Question 41

What is the centre of gravity (mass)?

Answer 41

The point where all the weight of an object acts through

Question 42

What will happen if the centre of gravity is above the pivot?

Answer 42

There will be no turning force

Question 43

What will happen if the centre of gravity is to the left or right of the pivot?

Answer 43

There will be a turning force