Topic 3 - Motion And Forces

Question 0

What is speed?

Answer 0

How FAST you are going with NO regard to direction

Question 1

What are speed and velocity measured in?

Answer 1

m/s(or km/h or mph)

Question 2

What is velocity?

Answer 2

How fast you are going WITH regard to direction. The distance in a particular direction is called displacement.

Question 3

What is displacement

Answer 3

The distance in a particular direction

Question 4

Velocity and displacement depend on what?

Answer 4

SIZE and DIRECTION

Question 5

What is acceleration?

Answer 5

How quickly a velocity is changing

Question 6

How is the change in velocity effected?

Answer 6

Change in SPEED or change in DIRECTION (or both)

Question 7

Is acceleration a vector quantity?

Answer 7

Yes

Question 8

What is a vector quantity?

Answer 8

It has a magnitude and direction

Question 9

Important facts on DISTANCE-TIME GRAPHS

Answer 9

• Gradient = speed
• Flat sections are where is has stopped
• Steeper the graph, faster it’s going
• Downhill lines = going back to starting point
• Curves = acceleration or deceleration
• Steepening curve = speeding up

Question 10

How do you calculate the speed of a distance-time graph?

Answer 10

Find the gradient- vertical / horizontal

Question 11

Important facts on velocity time graphs

Answer 11

• Gradient = acceleration
• Flat sections = steady speed
• Steeper the graph = greater acceleration or deceleration
• Uphill sections (/) = acceleration
• Downhill sections () = deceleration
• Area under any section on graph (or all of it) = distance travelled in that time interval
• A curve = changing acceleration

Question 12

How to find acceleration of velocity time graph

Answer 12

Find gradient = y / x = vertical / horizontal

Question 13

Forces on a stationary object?

Answer 13

• Gravity/weight (down)
• Reaction force (pushing up)

(They are equal)

Question 14

Forces on steady horizontal velocity with forces in balance

Answer 14

Thrust (forward)
Drag (backward)
Gravity/Weight (down)
Reaction (up)

Question 15

Forces on steady vertical velocity with forces in balance

Answer 15

Drag (up)

Weight/Gravity (down)

Question 16

Forces on horizontal acceleration with forces unbalanced

Answer 16

Only acceleration arrow labelled (forward)

Put arrows around car but no words except ‘acceleration’

Question 17

Forces on vertical acceleration with forces unbalanced

Answer 17

Less drag (upwards)

More weight (down) and acceleration (down)

Question 18

What is weight caused by and what is it measured in?

Answer 18

Caused by pull or gravity, and it’s a force measured in newtons

Question 19

Is mass a force?

Answer 19

NO!

Question 20

What is mass? What is it measured in?

Answer 20

How much ‘stuff’ in an object, measured in kg

Question 21

If you go to the moon, what is changed: your mass or your weight?

Answer 21

Your mass stays the SAME. Your weight CHANGES

Question 22

Falling object in a vacuum fall at the same rate or a different rate?

Answer 22

The SAME rate

Question 23

Why do falling objects in a vacuum accelerate at the same rate?

Answer 23

Because space (a vacuum) has no air resistance, so there is no resistance to slow down falling objects - the only acting force on an object is gravity.

Question 24

Objects falling through and atmosphere reach a what?

Answer 24

Terminal velocity

Question 25

Why do objects falling through an atmosphere reach a terminal velocity?

Answer 25

- When falling objects first set off, they have more force (weight/gravity) accelerating them than air resistance slowing them down - As speed increases, air resistance increases - Air resistance gradually increases and reduces the acceleration until it is equal to weight and gravity of falling object - When two forces are balanced, the object will not accelerate any more. It will have reached maximum speed - its terminal velocity.

Question 26

When two bodies interact, what happens to the force?

Answer 26

They exert force onto eachother

Question 27

If object A exerts force on Object B, what happens next?

Answer 27

Then object B exerts the exact opposite force (but same size) on object A.

Question 28

No resultant force means what for velocity?

Answer 28

No change in velocity

Question 29

To keep a steady speed of an object there should be how much resultant force?

Answer 29

ZERO! NONE!

Question 30

What does resultant force mean?

Answer 30

Acceleration

Question 31

If the resultant force acting on a body is not zero, it will accelerate in what direction?

Answer 31

The direction of the resultant force

Question 32

What happens to the acceleration or deceleration when the resultant force is big?

Answer 32

Acceleration and deceleration will be greater

Question 33

If there's an overall force, the object will..

Answer 33

Accelerate

Question 34

It the object has a steady speed, the forces are...

Answer 34

Balanced