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

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

Answer 8

Find the gradient- vertical / horizontal

Question 9

How to find acceleration of velocity time graph

Answer 9

Find gradient = y / x = vertical / horizontal

Question 10

Forces on a stationary object?

Answer 10

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

(They are equal)

Question 11

Forces on steady horizontal velocity with forces in balance

Answer 11

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

Question 12

Forces on steady vertical velocity with forces in balance

Answer 12

Drag (up)

Weight/Gravity (down)

Question 13

Forces on horizontal acceleration with forces unbalanced

Answer 13

Only acceleration arrow labelled (forward)

Put arrows around car but no words except ‘acceleration’

Question 14

Forces on vertical acceleration with forces unbalanced

Answer 14

Less drag (upwards)

More weight (down) and acceleration (down)

Question 15

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

Answer 15

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

Question 16

Is mass a force?

Answer 16

NO!

Question 17

What is mass? What is it measured in?

Answer 17

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

Question 18

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

Answer 18

Your mass stays the SAME. Your weight CHANGES

Question 19

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

Answer 19

The SAME rate

Question 20

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

Answer 20

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 21

Objects falling through and atmosphere reach a what?

Answer 21

Terminal velocity

Question 22

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

Answer 22

• 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 23

When two bodies interact, what happens to the force?

Answer 23

They exert force onto eachother

Question 24

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

Answer 24

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

Question 25

No resultant force means what for velocity?

Answer 25

No change in velocity

Question 26

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

Answer 26

ZERO! NONE!

Question 27

What does resultant force mean?

Answer 27

Acceleration

Question 28

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

Answer 28

The direction of the resultant force

Question 29

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

Answer 29

Acceleration and deceleration will be greater

Question 30

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

Answer 30

Accelerate

Question 31

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

Answer 31

Balanced

Question 32

Difference between speed and velocity?

Answer 32

Velocity is a vector, speed is not

Question 33

When all the forces on an object are balanced, what is the resultant force?

Answer 33

0

Question 34

How does doubling the size of the resultant force effect the acceleration?

Answer 34

The acceleration also doubles

Question 35

How does doubling the mass of an object effect the acceleration?

Answer 35

The acceleration halves

Question 36

What is the gravitational field strength of the Earth?

Answer 36

10 N/kg

Question 37

What is gravitational field strength measured in?

Answer 37

N/kg

Question 38

What are the three stages of falling?

Answer 38

- At the start, the object accelerates downwards because of its weight. There is no air resistance. There is a resultant force acting downwards. - As it gains speed, the object's weight stays the same, but the air resistance on it increases. There is a resultant force acting downwards. - Eventually, the object's weight is balanced by the air resistance. There is no resultant force and the object reaches a steady speed, called the terminal velocity.

Question 39

What are the two forces that affect a falling object?

Answer 39

Weight of object Air resistance