# P2.1 - Motion Flashcards

1
Q

State different ways to measure time (and cons)

A
```\+ use a stopwatch
\+ use a light gate
cons?
there is a reaction time that affects the accuracy and precision
2
Q

What is the equation for calculating average speed?

A
```total distance (m)
average speed (m/s) = ————————
total time (s)```
3
Q

How many meters are there in one mile?

A

1609m

4
Q

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

A

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)

5
Q

What is displacement and is it a vector or scalar?

A

+ The distance from the place you travel

+ is a vector (has direction)

6
Q

What is speed?

A

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

7
Q

What is velocity?

A

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

8
Q

What is the change in velocity per second called?

A

acceleration

9
Q

what is the equation for acceleration?

A

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

10
Q

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

A

deceleration

11
Q

What does a (diagonal) straight line mean on a distance time graph?

A

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

12
Q

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

A

the object is not moving

13
Q

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

A

The steeper the line, the faster the object is travelling

14
Q

How do you calculate speed from a distance time graph?

A

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

15
Q

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

A

+ a distance-time graph is scalar

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

16
Q

what is the equation for velocity?

A

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

17
Q

What does the gradient on a graph tell you?

A

the rate of change with time

18
Q

what does the change of speed or velocity tell you?

A

acceleration

19
Q

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

A

as a minus number

ie. -0.35 m/s^2

20
Q

What is the equation of motion?

A

v^2 - u^2 = 2as

21
Q

What is the equation to calculate kinetic energy?

A

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

22
Q

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

A

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

bro said m/s^2 how did this girl pattern up to get a grade 9
- if she can do it anyone can

23
Q

Convert 30mph to m/s

A
```1 mile = 1609m
1hr = 60m
60m = 3600s
d              48 270
s = ——   =  ————
t                3 600
= 13m/s```
24
Q

How many seconds are there in an hour?

A

3600

25
Q

How do you represent a vector?

A

With an arrow (length shows magnitude)

26
Q

what is the unit of acceleration?

A

m/s^2

27
Q

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

A

In the opposite direction

28
Q

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

A

29
Q

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

A

that the object is not moving

30
Q

how do you calculate speed on a distance time graph?

A

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

31
Q

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

A
• A distance time graph only shows the total distance travelled
• on displacement time graph, the gradient can be negative
32
Q

what does the gradient represent on a displacement time graph?

A

the velocity of an object

33
Q

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

A

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

34
Q

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

A

measure the area below the line

35
Q

what unit is velocity measured in?

A

m/s

36
Q

what unit is kinetic energy measured in?

A

Joules (J)

37
Q

What is human reaction time?

A

0.2s

38
Q

describe in detail how to measure your walking speed

A
• measure the distance you walked

- divide it by the time taken to walk that distance

39
Q

Why does kinetic energy quadruple when the speed is squared?

A

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

40
Q

Is acceleration a vector or a scalar?

A

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

41
Q

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

A

Yes, as it has changed it’s speed

42
Q

state methods to measure distance:

A

metre ruler
tape measures
ultrasound? (bit far-fetched but ig it works)