Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

SA N5 Physics > Dynamics > Flashcards

Dynamics Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

Describe how to measure average speed

A
  • Mark a start line and finish line
  • Measure the distance between the start and finish line with a metre stick
  • Start a stopwatch when the object crosses the start line and stop it when it crosses the finish line
  • Calculate the average speed = distance between start and finish line / time on stopwatch
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe how to measure average speed using the equipment below

A
  • Two light gates are connected to a timer
  • The car rolls down the slope
  • When the mask breaks the fist lightgate beam it starts the timer
  • When the mask breaks the the second lightgate beam it stops the timer
  • Measure the distance between the two lightgates using a metre stick
  • Calculate the speed = distance between lightgates / time on timer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe how to use the equipment below to calculate the instantaneous speed of the car

A
  • Measure the length of the mask using a ruler
  • Roll the car down the slope
  • When the mask breaks the beam it starts the timer connected to the lightgate
  • When the mask has passed through, the beam is restored and the timer stops
  • Speed = length of mask / time on timer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Explain the difference between average and instantaneous speed

A

Average is over a long period of time. Instantaneous speed is the speed over a very short period of time (an instant)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

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

A

A scalar needs size/magnitude to be described correctly. A vector quantity needs size/magnitude and direction to be described correctly.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Name 3 vector quantities

A
  • Displacement
  • Velocity
  • Acceleration
  • Force
  • Weight
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Name 3 scalar quantities

A
  • Distance
  • Time
  • Speed
  • Mass
  • Energy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the difference between distance and displacement?

A

Distance is the length of the path you actually take and is a scalar. Displacement is the straight line distance between the start point and finish point and includes a direction as it is a vector.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the difference between speed and velocity?

A

Speed is a scalar and is equal to distance divided by time. Velocity is a vector and is displacement divided by time, with a direction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is speed?

A

Distance travelled per second

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is velocity?

A

Displacement travelled per second

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is acceleration?

A

Acceleration is the rate of change of velocity or the change in velocity per second

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is meant by an acceleration of 15 ms-2?

A

The velocity increases by 15 ms-1 every second

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Explain how to measure the acceleration of the car using the equipment below and a stop watch

A
  • The car starts from rest so u = 0 ms-1
  • When the car is released start the stop watch and stop the stopwatch when it reaches the lightgate
  • This is t, the time for the change in velocity
  • When the mask passes through the lightgate, the electronic timer records the time
  • Measure the length of the card using a ruler
  • The final velocity, v = length of mask / time on electronic timer
  • Calculate acceleration, a = (v-u)/t
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Explain how to measure acceleration using the equipment below and a stop watch

A
  • When the mask passes through the 1st light gate the electronic timer records this time
  • Measure the length of the mask using a ruler
  • The initial velocity, u = length of card / time on timer
  • As the car rolls down the ramp, start the stop watch when it reaches the 1st light gate and when it reaches the 2nd light gate stop the stop watch
  • This is t, the time for the change in velocity
  • When the mask passes through the 2nd light gate, the electronic timer records the time
  • The final velocity, v = length of mask / time on timer
  • Calculate acceleration, a = (v-u)/t
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does this velocity-time graph show?

A

Constant velocity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does this velocity-time graph show?

A

Constant acceleration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What does this velocity-time graph show?

A

Constant deceleration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens to the object at point X?

A

It changes direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What does the area under the velocity-time graph give?

A

The distance travelled

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Describe how to calculate acceleration from a velocity-time graph

A
  • Pick 2 points on the slope
  • u = initial speed, read it off the graph
  • v = final speed, read it off the graph
  • t = time to go from the initial speed to the final speed
  • Calculate acceleration using a = (v-u)/t
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the 3 effects a force can have?

A
  • Change the speed of an object
  • Change the direction of travel of an object
  • Change the shape of an object
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is a balanced force?

A

Equal forces acting in opposite directions

24
Q

Newtons 1st Law is about balanced forces. What 2 things can happen if a balanced force acts on an object?

A
  • Remains at rest (stationary)
  • Travels at a constant speed in a straight line
25
Q

An object travels at a constant speed of 10 ms-1. What can be said about the forces acting on it?

A

The forces are balanced

26
Q

What causes friction?

A

Two surfaces rubbing together

27
Q

What is friction?

A

A force that opposes the motion of an object

28
Q

How can you increase friction?

A
  • Increase the area of the rubbing surfaces
  • Make the surfaces rubbing together rougher
  • Push the surfaces together more
  • Increase the speed that the surfaces are rubbing together
29
Q

How can you decrease friction?

A
  • Decrease the area of the rubbing surfaces
  • Make the surfaces rubbing together smoother
  • Push the surfaces together less
  • Decrease the speed that the surfaces are rubbing together
  • Lubricate/oil/wax the surfaces
  • Streamline the object
30
Q

What is meant by streamlining?

A

Changing the shape of an object to reduce air/water resistance/drag

31
Q

Describe a streamlined shape

A
  • Low to the ground
  • Smooth
  • Have curves
32
Q

What will an unbalanced force cause?

A

Acceleration

33
Q

Explain how a seatbelt works in terms of Newtons Laws

A
  • When a car travels at a constant velocity, the forces on it are balanced (Newtons 1st Law)
  • If the brakes are applied, they provide an unbalanced force that stops the car (Newtons 2nd Law)
  • The passengers continue to travel at a constant speed in a straight line (Newtons 1st Law)
  • The seatbelt provides an unbalanced force to decelerate the passenger to zero without hitting the windscreen (Newtons 2nd Law)
34
Q

What is work?

A

It is the measure of the energy used to move an object over a distance using a force

35
Q

What is the difference between mass and weight?

A
  • Mass is a measure of the particles that make up an object, in kg and cannot vary.
  • Weight is a force caused by the gravitational field strength of a planet, in N and varies according to where in the universe the object is
36
Q

What is meant by gravitational field strength?

A

Force per unit mass

37
Q

An astronaut has a mass of 50kg. What will happen to the astronaut’s mass on the Moon?

A

It stays at 50kg. Mass does not change

38
Q

An astronaut has a mass of 50kg. What will happen to the astronaut’s weight on the Moon?

A

The weight will decrease as there is a lower gravitational field strength on the Moon

39
Q

How can a space rocket be slowed down in space?

A

Reverse the thrusters to provide an unbalanced force backwards and produce a deceleration

40
Q

What is the weight of an object in freefall?

A

0 Newtons

41
Q

Explain how a skydiver reaches terminal velocity

A
  • When the skydiver jumps out of a plane, his initial vertical velocity is zero
  • His weight causes him to accelerate towards the ground (Weight = Force = ma)
  • As the skydivers velocity increases the air resistance upwards increases too
  • So the unbalanced force downwards becomes less, so there is less acceleration towards the ground (Weight - air resistance = unbalanced force = ma)
  • Eventually the weight downwards is equal and opposite to the air resistance upwards
  • This is a balanced force so the skydiver reaches terminal velocity
42
Q

What does the path of a projectile launched horizontally look like?

A

Curve

43
Q

Explain why a projectile follows a curved trajectory

A
  • It has a constant horizontal velocity
  • It has a constant vertical acceleration downwards due to gravity
44
Q

Describe how a cyclist can streamline themselves

A
  • Crouch over the handlebars
  • Wear tight Lycra clothing
  • Specially shaped helmet
45
Q

A car is travelling at a constant velocity of 25ms-1, the engine is producing a force of 4000N. What is the size of the frictional forces acting on the car?

A

4000N backwards

46
Q

Which line on the graph represents the largest acceleration?

A

Blue line - it has the steepest gradient

47
Q

For a projectile fired horizontally, what would the horizontal velocity-time graph look like?

A

Constant horizontal velocity - therefore a straight horizontal line

48
Q

For a projectile fired horizontally, what would the vertical velocity-time graph look like?

A

It would show a constant acceleration, a line of gradient = 9.8ms-2

49
Q

Explain how a satellite stays in orbit

A
  • Satellite has a constant horizontal velocity
  • Satellite has a constant vertical acceleration due to the gravitational field strength of the planet
  • This gives a curved trajectory
  • The planet is curved so the satellite remains in orbit
50
Q

If an object is projected horizontally from a cliff, how can the height of the cliff be calculated?

A
  • Sketch a vertical velocity-time graph
  • Due to the gravitational field strength the velocity will increase vertically by 9.8ms-2
  • Calculate the area under the velocity-time graph
  • This is equal to the vertical height of the cliff
51
Q

If an object is projected horizontally or dropped, how can the vertical velocity just before it hits the ground be calculated

A
  • Use a = (v-u)/t
  • u is 0ms-1
  • a is 9.8ms-2
  • t is the time it falls for
  • a = (v-0)/t
  • v = at
52
Q

What does the gradient on a velocity-time graph represent?

A

The acceleration

53
Q

What is conservation of energy?

A

Energy cannot be created or destroyed it can only be transferred from one form to another

54
Q

When does an object have potential energy?

A

When it is lifted through a height

55
Q

When does an object have kinetic energy?

A

When it is moving

56
Q

When is work done?

A

When a force is exerted over a distance

57
Q

Explain the energy change as a sledge slides down a hill

A
  • At the start, the sledge has potential energy
  • As it starts to slide down the hill, it loses potential energy and gains kinetic energy
  • At the bottom of the hill, the sledge has no potential energy as it has all been transferred to kinetic energy
  • At any point on the slope, the potential energy + the kinetic energy = potential energy at the top of the slope

SA N5 Physics (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions