P2.1 - Motion

Question 1

State different ways to measure distance

Answer 1

+ use a ruler
+ ultrasound (high frequency sound waves)
-> measures the time taken off by pulse to travel there and back
uses values and speed of pulse to work out distance

Question 2

State different ways to measure time (and cons)

Answer 2

\+ use a stopwatch 
\+ use a light gate 
cons? 
there is a reaction time that affects the accuracy and precision 
is expensive to buy

Question 3

What is the equation for calculating average speed?

Answer 3

total distance (m)
average speed (m/s) = ————————
                                                   total time (s)

Question 4

How many meters are there in one mile?

Answer 4

1609m

Question 5

What is the difference between a scalar and a vector measurement?

Answer 5

Vector has a magnitude (size) and direction -> represented as an arrow ie. force

Scalar has only magnitude (size) but no direction.
ie. time on a stopwatch (10s)

Question 6

What is displacement and is it a vector or scalar?

Answer 6

+ The distance from the place you travel

+ is a vector (has direction)

Question 7

What is speed?

Answer 7

+ a scalar quantity (has no direction)
+ is a measurement
ie. 15m/s

Question 8

What is velocity?

Answer 8

+ A vector quantity
+ has a direction as well as a magnitude
ie. 15m/s south
+ is in a certain direction

Question 9

What is the change in velocity per second called?

Answer 9

acceleration

Question 10

what is the equation for acceleration?

Answer 10

change in velocity (m/s)
acceleration (m/s^-2) = ——————————
time (s)

Question 11

What is the term when a vehicle slows down (acceleration)?

Answer 11

deceleration

Question 12

What does a straight line mean on a distance time graph?

Answer 12

the object’s speed is constant because the gradient doesn’t change

Question 13

What does a horizontal line mean on a distance time graph?

Answer 13

the object is not moving

Question 14

What does a steep line mean on a distance time graph?

Answer 14

The steeper the line, the faster the object is travelling

Question 15

How do you calculate speed from a distance time graph?

Answer 15

1) Draw a right-angled triangle underneath the line
2) Find the change in distance and the change in time
3) Use the equation of speed to find out the answer

Question 16

What is the difference between a distance-time graph and a displacement-time graph?

Answer 16

+ a distance-time graph is scalar

+ a displacement-time graph’s gradient has a velocity

Question 17

what is the equation for velocity?

Answer 17

change in displacement
velocity = ——————————
time

Question 18

What does the gradient on a graph tell you?

Answer 18

the rate of change with time

Question 19

what does the change of speed or velocity tell you?

Answer 19

acceleration

Question 20

if the initial velocity is higher than the final velocity, how is the acceleration shown?

Answer 20

as a minus number

ie. -0.35 m/s^2

Question 21

What is the equation of motion?

Answer 21

(final velocity (m/s))^2 - (initial velocity (m/s))^2

= 2 x acceleration (m/s^2) x distance (m)

Question 22

What is the equation to calculate kinetic energy?

Answer 22

kinetic energy (J) = 0.5 x mass (kg) x speed (m/s))^2

Question 23

If a question says that an object is at rest, what is its initial velocity?

Answer 23

0 m/s^2 (since it is not moving)

Question 24

Convert 30mph to m/s

Answer 24

1 mile = 1609m 
1hr = 60m
60m = 3600s 
          d              48 270
s = ——   =  ————
           t                3 600
= 13m/s

Question 25

How many seconds are there in an hour?

Answer 25

3600

Question 26

How do you represent a vector?

Answer 26

With an arrow (length shows magnitude)

Question 27

what is the unit of acceleration?

Answer 27

m/s^2

Question 28

how is an object moving if it has a negative velocity?

Answer 28

In the opposite direction

Question 29

How do you figure out the speed on a distance-time graph?

Answer 29

Look at the gradient (speed is equal to gradient)

Question 30

what does a horizontal line mean on a distance-time graph?

Answer 30

that the object is not moving

Question 31

how do you calculate speed on a distance time graph?

Answer 31

draw a right-angled triangle and divide the change in distance by change in time

Question 32

how is a distance time graph different from a displacement time Graph?

Answer 32

• A distance time graph only shows the total distance travelled
• on displacement time graph, the gradient can be negative

Question 33

what does the gradient represent on a displacement time graph?

Answer 33

the velocity of an object

Question 34

how do you calculate acceleration from a velocity-time graph?

Answer 34

change in velocity
————————
change in time

Question 35

how do you calculate distance travelled on a velocity time graph?

Answer 35

measure the area below the line

Question 36

what unit is velocity measured in?

Answer 36

m/s

Question 37

what unit is kinetic energy measured in?

Answer 37

Joules (J)

Question 38

What is human reaction time?

Answer 38

0.2s

Question 39

describe in detail how to measure your walking speed

Answer 39

• measure the distance you walked

- divide it by the time taken to walk that distance

Question 40

Why does kinetic energy quadruple when the speed is squared?

Answer 40

Because it is relative to double the speed of the object (so 2x2 =4)

Question 41

Is acceleration a vector or a scalar?

Answer 41

A vector, as it is the rate of change in VELOCITY not speed.

So if an object is at a constant speed, but changing direction, it is still accelerating

Question 42

If a body is moving and it starts to slow down, is it still accelerating?

Answer 42

Yes, as it has changed it’s speed