# Topic 2 - Motion and Forces COMPLETE PK Flashcards

1 Runner A finishes a race in less time than runner B. Who is faster?

runner A

2 What two measurements are needed to calculate a speed?

distance and time

3 What is the SI unit for speed?

m/s

4 What does acceleration mean?

speeding up or slowing down

5 What is a force?

push or pull

6 How do we represent forces on diagrams?

arrows, with length depending on size of force

7 What does mass mean?

amount of substance

8 What is the unit for mass?

kilogram

9 What does a vector have that a scalar does not?

direction

10 Name a scalar and a vector measured in metres.

distance, displacement

11 Name a scalar and a vector measured in metres/second.

speed, velocity

12 Name a vector with units of newtons.

force or weight

13 Is mass a vector or scalar?

scalar

14 Is energy a vector or scalar?

scalar

15 What is acceleration?

a change in velocity

16 Why is acceleration a vector?

it is measuring a change in another vector

17 What is the difference between speed and velocity?

velocity has a direction/is a vector

18 What is the equation for calculating speed?

speed = distance / time

19 What is the SI unit for speed?

metres per second

20 What is average speed?

total distance / time for whole journey

21 What is the equation for calculating distance?

distance = speed x time

22 How is a constant speed shown on a distance/time graph?

straight, sloping line

23 What does a horizontal line on a distance/time graph show?

stationary object

24 What is the speed of sound in air?

approximately 330m/s

25 How is a stationary object shown on a distance/time graph?

horizontal line

26 How can you tell which part of a journey shown on a distance/time graph has the highest speed?

steepest line

27 How can you calculate velocity from a distance/time graph?

gradient of line

28 What does acceleration mean?

change in velocity in time

29 What are the units for acceleration?

metres per second squared

30 In the acceleration equation, what does u stand for?

initial velocity

31 In the acceleration equation, what does v stand for?

final velocity

32 What is the equation for calculating acceleration?

change in velocity/time, or

33 What is the acceleration due to gravity?

10m/s2 to 1 sig. fig or 9.8m/s2 to 2 sig. fig.

34 What is the force that pulls us towards the Earth?

gravity

35 What is ‘drag’ another name for?

air resistance or water resistance

36 What are balanced forces?

forces of the same size in opposite directions

37 What do we call the forwards force produced by an aeroplane’s engine or propeller?

thrust

38 What word describes both the speed and direction of movement of an object?

velocity

39 What is the name for a single force on an object with the same effect as all the forces combined?

resultant

40 How do we describe the forces on an object when the force in one direction is bigger than the force in the other?

unbalanced

41 Two forces on an object are in the same direction. How do we calculate the resultant force?

add

42 Two forces on an object are in opposite directions. How do we calculate the resultant force?

find the difference between them

43 What does the length of a force arrow on a diagram represent?

size of force

44 An aeroplane has thrust of 2000N and drag of 1800N. What is the resultant?

200N forwards

45 Air resistance on a cyclist is 20N and friction is 5N. What is the total force trying to slow the cyclist down?

25N backwards

46 Name a vector quantity that changes as a car drives at constant speed around a roundabout.

velocity

47 What are unbalanced forces?

forces of different sizes in opposite directions

48 What is the direction of the resultant force on a car that is speeding up?

forwards

49 What is the direction of the resultant force on a bicycle that is slowing down?

backwards

50 How does a sideways resultant force affect the velocity of a moving object?

changes its direction

51 How can the pilot of an aeroplane make the plane gain speed upwards?

increase the lift/upwards force

52 How do balanced forces affect the velocity of a moving car?

The car continues with the same velocity.

53 You pedal harder on a bicycle. What happens?

you accelerate/get faster