True or False? A person running typically moves at about 6 m/s.

False. The typical running speed is about 3 m/s . 6 m/s is closer to a cycling speed.

Why do typical speeds for a person walking vary from one individual to another?

Typical walking speeds vary because of differences in age , fitness , terrain , and the distance being walked. These factors mean there is no single fixed value.

A typical family car accelerates from 0 m/s to 27 m/s in about 10 seconds, giving an acceleration of ..........

A typical family car accelerates from 0 m/s to 27 m/s in about 10 seconds, giving an acceleration of 2.7 m/s²

True or False? A sprinter accelerates more rapidly than a falling object.

False. A falling object accelerates at about 10 m/s² due to gravity. A sprinting human accelerates at roughly 3–4 m/s² , which is much less.

What does the acceleration of an object measure?

Acceleration measures how quickly an object's velocity changes . It is calculated as the change in velocity divided by the time taken.

State the SI base units of the Newton (N) .

kg m s -2 Derived from Force = mass × acceleration.

True or False? To convert a temperature from Celsius to Kelvin, you subtract 273.

False. To convert from Celsius to Kelvin , you add 273 . Subtracting 273 converts from Kelvin to Celsius.

State the SI base units of the Joule (J) .

kg m 2 s -2 Derived from Energy = ½ × mass × velocity².

Complete the prefix table. Prefix Symbol Power of ten giga G mega M kilo k milli m micro μ nano n

Complete the prefix table. Prefix Symbol Power of ten giga G 10 9 mega M 10 6 kilo k 10 3 milli m 10 -3 micro μ 10 -6 nano n 10 -9

How many seconds are there in one hour, and how do you convert hours into seconds?

There are 3600 seconds in one hour (60 minutes × 60 seconds). To convert from hours to seconds, multiply by 3600 ; to convert from seconds to hours, divide by 3600.

True or False? The Pascal (Pa) in SI base units is kg m -1 s -2 .

True. Pressure = Force ÷ Area, so Pa = N/m 2 = (kg m s -2 )/m 2 = kg m -1 s -2 .

Why do physicists use prefix notation for very large or very small quantities?

Prefix notation (e.g. km, μA, GHz) makes very large or very small values easier to write and read. Physical quantities can span over 30 powers of ten , so prefixes avoid writing many zeros.

The seven units from which every other unit in physics can be derived are called ..........

The seven units from which every other unit in physics can be derived are called SI base units

Define reaction time .

Reaction time is the time that passes between seeing something and reacting to it .

True or False? The typical reaction time for an alert person is between 0.2 and 0.9 seconds.

True. An alert person typically reacts within 0.2–0.9 s . Factors such as tiredness or distraction increase this value.

In the ruler drop experiment, what does a greater distance fallen indicate?

A greater distance fallen indicates a longer reaction time . The ruler falls further before the person catches it, showing they took more time to respond to seeing it move.

In the ruler drop test, Person A releases the ruler and Person B catches it. The measurement recorded is the ..........

In the ruler drop test, Person A releases the ruler and Person B catches it. The measurement recorded is the distance the ruler fell

Why does the ruler drop method not directly measure reaction time?

The ruler drop method measures the distance the ruler falls, not time directly. The distance can be used to calculate the time using kinematics, but the method itself only records how far the ruler dropped.

True or False? In the ruler drop test, Person B should catch the ruler as soon as they feel it move.

False. Person B should catch the ruler as soon as they see it move. Reaction time is the delay between seeing the event and responding, not feeling it.

Define stopping distance .

Stopping distance is the total distance travelled from when the driver realises they need to stop to when the vehicle comes to a complete halt . Stopping distance = thinking distance + braking distance

True or False? If a car's speed doubles, its braking distance increases by a factor of 4.

True. Braking distance is proportional to speed² . Doubling the speed means (2)² = 4 times the braking distance, because kinetic energy = ½mv².

Define thinking distance .

Thinking distance is the distance travelled by a vehicle from when the driver realises they need to brake to when they apply the brakes . Thinking distance = speed × reaction time

Give three factors that increase a driver's thinking distance.

Thinking distance is increased by tiredness , distractions (such as using a mobile phone), and intoxication (alcohol or drugs). All three increase the driver's reaction time , so the car travels further before braking begins.

State whether each factor affects thinking distance, braking distance, or both. Factor Affects Icy road Driver tiredness Worn tyres Higher vehicle speed

State whether each factor affects thinking distance, braking distance, or both. Factor Affects Icy road Braking distance Driver tiredness Thinking distance Worn tyres Braking distance Higher vehicle speed Both

True or False? A large deceleration is dangerous because it requires a large force to be exerted on the vehicle and its occupants.

True. By Newton's Second Law, F = ma : a large deceleration ( a ) for a given mass ( m ) demands a large force ( F ). This force can cause injuries such as whiplash.

Why is whiplash associated with large vehicle decelerations?

During a sudden deceleration, the vehicle slows rapidly but the occupant's head continues moving forward momentarily. This causes the head to snap relative to the body, producing the neck injury known as whiplash .

Why does a heavily loaded lorry have a greater braking distance than a car travelling at the same speed?

A lorry has a much greater mass , so it has greater kinetic energy at the same speed. More work must be done by the brakes to bring it to rest, resulting in a longer braking distance .

State the equation linking braking force, braking distance and kinetic energy . (Higher Tier Only)

Braking force × braking distance = ½mv² Work done by the brakes equals the kinetic energy transferred to heat and sound.

True or False? Braking distance is proportional to a vehicle's speed. (Higher Tier Only)

False. Braking distance is proportional to speed² (not speed). If speed doubles, braking distance increases by a factor of 4 .

A car of mass 1500 kg travelling at 18 m/s has a braking distance of 24 m. Estimate the braking force. (Higher Tier Only)

Using braking force × braking distance = ½mv² : Braking force = (½ × 1500 × 18²) ÷ 24 = 243 000 ÷ 24 ≈ 10 000 N

At very high speeds, brakes get hot and become less effective. This reduces the braking force, causing the braking distance to ......... (Higher Tier Only)

At very high speeds, brakes get hot and become less effective. This reduces the braking force, causing the braking distance to increase even further

Why is braking distance proportional to speed squared rather than speed? (Higher Tier Only)

Braking distance depends on the kinetic energy the brakes must remove. Kinetic energy = ½mv² , which contains speed squared. Doubling speed quadruples KE, so the brakes must do four times as much work, giving four times the braking distance .

True or False? The work done by brakes when stopping a vehicle equals the vehicle's kinetic energy before braking. (Higher Tier Only)

True. The brakes transfer all the vehicle's kinetic energy into thermal energy (and some sound), so the work done equals ½mv² .

State the stopping distance at 20 mph (Highway Code) .

12 m At 60 mph the stopping distance rises to 73 m.

True or False? On a velocity-time graph of an emergency stop, the thinking distance is represented by the area under the graph while the vehicle decelerates.

False. The thinking distance is the area under the graph during the constant velocity section (before braking). The area during deceleration represents the braking distance .

On a velocity-time graph of an emergency stop, how is the braking distance identified?

The braking distance is the area under the graph during the section where velocity decreases to zero. This region is typically a triangle, so the area = ½ × base × height .

Stopping distance increases with speed because both thinking distance and braking distance ..........

Stopping distance increases with speed because both thinking distance and braking distance increase as the vehicle moves faster

How does thinking distance vary with speed, and what does this tell us about the graph?

Thinking distance is directly proportional to speed. The graph of thinking distance against speed is a straight line through the origin , because thinking distance = speed × reaction time and reaction time is constant.

True or False? A tired driver's thinking distance against speed graph has the same gradient as an alert driver's. (Higher Tier Only)

False. A tired driver has a longer reaction time , so their thinking distance is greater at every speed. The graph has a steeper gradient than an alert driver's.

A car travelling at moderate speed (~20 m/s) stops in a collision in 0.1 s. Estimate the deceleration.

Using a = Δv ÷ t: a = (0 − 20) ÷ 0.1 = −200 m/s 2 The negative sign shows the force acts opposite to the direction of motion.

For a passenger of mass 70 kg decelerating at 200 m/s 2 , the estimated force on the passenger is ..........

For a passenger of mass 70 kg decelerating at 200 m/s 2 , the estimated force on the passenger is 14 000 N

GCSEPhysicsOCRPhysics A (Gateway)Flashcards8. Global ChallengesPhysics on the Move

Physics on the Move (OCR GCSE Physics A (Gateway)): Flashcards

Exam code: J249

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FrontEstimating Speeds & Accelerations
State the typical walking speed.

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Cards in this collection (44)

State the typical walking speed.
1.5 m/s
True or False?
A person running typically moves at about 6 m/s.
False.
The typical running speed is about 3 m/s. 6 m/s is closer to a cycling speed.
State the typical cycling speed.
6 m/s
Why do typical speeds for a person walking vary from one individual to another?
Typical walking speeds vary because of differences in age, fitness, terrain, and the distance being walked. These factors mean there is no single fixed value.
A typical family car accelerates from 0 m/s to 27 m/s in about 10 seconds, giving an acceleration of ..........
A typical family car accelerates from 0 m/s to 27 m/s in about 10 seconds, giving an acceleration of 2.7 m/s²
True or False?
A sprinter accelerates more rapidly than a falling object.
False.
A falling object accelerates at about 10 m/s² due to gravity. A sprinting human accelerates at roughly 3–4 m/s², which is much less.
What does the acceleration of an object measure?
Acceleration measures how quickly an object's velocity changes. It is calculated as the change in velocity divided by the time taken.
State the typical speed of a passenger plane.
250 m/s
State the SI base units of the Newton (N).
kg m s^-2
Derived from Force = mass × acceleration.
True or False?
To convert a temperature from Celsius to Kelvin, you subtract 273.
False.
To convert from Celsius to Kelvin, you add 273. Subtracting 273 converts from Kelvin to Celsius.
State the SI base units of the Joule (J).
kg m² s^-2
Derived from Energy = ½ × mass × velocity².
Complete the prefix table.
Prefix
Symbol
Power of ten
giga
G
mega
M
kilo
k
milli
m
micro
μ
nano
n
Complete the prefix table.
Prefix
Symbol
Power of ten
giga
G
10⁹
mega
M
10⁶
kilo
k
10³
milli
m
10^-3
micro
μ
10^-6
nano
n
10^-9
How many seconds are there in one hour, and how do you convert hours into seconds?
There are 3600 seconds in one hour (60 minutes × 60 seconds). To convert from hours to seconds, multiply by 3600; to convert from seconds to hours, divide by 3600.
True or False?
The Pascal (Pa) in SI base units is kg m^-1 s^-2.
True.
Pressure = Force ÷ Area, so Pa = N/m² = (kg m s^-2)/m² = kg m^-1 s^-2.
Why do physicists use prefix notation for very large or very small quantities?
Prefix notation (e.g. km, μA, GHz) makes very large or very small values easier to write and read. Physical quantities can span over 30 powers of ten, so prefixes avoid writing many zeros.
The seven units from which every other unit in physics can be derived are called ..........
The seven units from which every other unit in physics can be derived are called SI base units
Define reaction time.
Reaction time is the time that passes between seeing something and reacting to it.
True or False?
The typical reaction time for an alert person is between 0.2 and 0.9 seconds.
True.
An alert person typically reacts within 0.2–0.9 s. Factors such as tiredness or distraction increase this value.
In the ruler drop experiment, what does a greater distance fallen indicate?
A greater distance fallen indicates a longer reaction time. The ruler falls further before the person catches it, showing they took more time to respond to seeing it move.
In the ruler drop test, Person A releases the ruler and Person B catches it. The measurement recorded is the ..........
In the ruler drop test, Person A releases the ruler and Person B catches it. The measurement recorded is the distance the ruler fell
Why does the ruler drop method not directly measure reaction time?
The ruler drop method measures the distance the ruler falls, not time directly. The distance can be used to calculate the time using kinematics, but the method itself only records how far the ruler dropped.
True or False?
In the ruler drop test, Person B should catch the ruler as soon as they feel it move.
False.
Person B should catch the ruler as soon as they see it move. Reaction time is the delay between seeing the event and responding, not feeling it.
Define stopping distance.
Stopping distance is the total distance travelled from when the driver realises they need to stop to when the vehicle comes to a complete halt.
Stopping distance = thinking distance + braking distance
True or False?
If a car's speed doubles, its braking distance increases by a factor of 4.
True.
Braking distance is proportional to speed². Doubling the speed means (2)² = 4 times the braking distance, because kinetic energy = ½mv².
Define thinking distance.
Thinking distance is the distance travelled by a vehicle from when the driver realises they need to brake to when they apply the brakes.
Thinking distance = speed × reaction time
Give three factors that increase a driver's thinking distance.
Thinking distance is increased by tiredness, distractions (such as using a mobile phone), and intoxication (alcohol or drugs). All three increase the driver's reaction time, so the car travels further before braking begins.
State whether each factor affects thinking distance, braking distance, or both.
Factor
Affects
Icy road
Driver tiredness
Worn tyres
Higher vehicle speed
State whether each factor affects thinking distance, braking distance, or both.
Factor
Affects
Icy road
Braking distance
Driver tiredness
Thinking distance
Worn tyres
Braking distance
Higher vehicle speed
Both
True or False?
A large deceleration is dangerous because it requires a large force to be exerted on the vehicle and its occupants.
True.
By Newton's Second Law, F = ma: a large deceleration (a) for a given mass (m) demands a large force (F). This force can cause injuries such as whiplash.
Why is whiplash associated with large vehicle decelerations?
During a sudden deceleration, the vehicle slows rapidly but the occupant's head continues moving forward momentarily. This causes the head to snap relative to the body, producing the neck injury known as whiplash.
Why does a heavily loaded lorry have a greater braking distance than a car travelling at the same speed?
A lorry has a much greater mass, so it has greater kinetic energy at the same speed. More work must be done by the brakes to bring it to rest, resulting in a longer braking distance.
State the equation linking braking force, braking distance and kinetic energy. (Higher Tier Only)
Braking force × braking distance = ½mv²
Work done by the brakes equals the kinetic energy transferred to heat and sound.
True or False?
Braking distance is proportional to a vehicle's speed. (Higher Tier Only)
False.
Braking distance is proportional to speed² (not speed). If speed doubles, braking distance increases by a factor of 4.
A car of mass 1500 kg travelling at 18 m/s has a braking distance of 24 m. Estimate the braking force. (Higher Tier Only)
Using braking force × braking distance = ½mv²:
Braking force = (½ × 1500 × 18²) ÷ 24 = 243 000 ÷ 24 ≈ 10 000 N
At very high speeds, brakes get hot and become less effective. This reduces the braking force, causing the braking distance to ......... (Higher Tier Only)
At very high speeds, brakes get hot and become less effective. This reduces the braking force, causing the braking distance to increase even further
Why is braking distance proportional to speed squared rather than speed? (Higher Tier Only)
Braking distance depends on the kinetic energy the brakes must remove. Kinetic energy = ½mv², which contains speed squared. Doubling speed quadruples KE, so the brakes must do four times as much work, giving four times the braking distance.
True or False?
The work done by brakes when stopping a vehicle equals the vehicle's kinetic energy before braking. (Higher Tier Only)
True.
The brakes transfer all the vehicle's kinetic energy into thermal energy (and some sound), so the work done equals ½mv².
State the stopping distance at 20 mph (Highway Code).
12 m
At 60 mph the stopping distance rises to 73 m.
True or False?
On a velocity-time graph of an emergency stop, the thinking distance is represented by the area under the graph while the vehicle decelerates.
False.
The thinking distance is the area under the graph during the constant velocity section (before braking). The area during deceleration represents the braking distance.
On a velocity-time graph of an emergency stop, how is the braking distance identified?
The braking distance is the area under the graph during the section where velocity decreases to zero. This region is typically a triangle, so the area = ½ × base × height.
Stopping distance increases with speed because both thinking distance and braking distance ..........
Stopping distance increases with speed because both thinking distance and braking distance increase as the vehicle moves faster
How does thinking distance vary with speed, and what does this tell us about the graph?
Thinking distance is directly proportional to speed. The graph of thinking distance against speed is a straight line through the origin, because thinking distance = speed × reaction time and reaction time is constant.
True or False?
A tired driver's thinking distance against speed graph has the same gradient as an alert driver's. (Higher Tier Only)
False.
A tired driver has a longer reaction time, so their thinking distance is greater at every speed. The graph has a steeper gradient than an alert driver's.
A car travelling at moderate speed (~20 m/s) stops in a collision in 0.1 s. Estimate the deceleration.
Using a = Δv ÷ t: a = (0 − 20) ÷ 0.1 = −200 m/s²
The negative sign shows the force acts opposite to the direction of motion.
For a passenger of mass 70 kg decelerating at 200 m/s², the estimated force on the passenger is ..........
For a passenger of mass 70 kg decelerating at 200 m/s², the estimated force on the passenger is 14 000 N

Prefix	Symbol	Power of ten
giga	G
mega	M
kilo	k
milli	m
micro	μ
nano	n

Prefix	Symbol	Power of ten
giga	G	10⁹
mega	M	10⁶
kilo	k	10³
milli	m	10^-3
micro	μ	10^-6
nano	n	10^-9

Factor	Affects
Icy road
Driver tiredness
Worn tyres
Higher vehicle speed

Factor	Affects
Icy road	Braking distance
Driver tiredness	Thinking distance
Worn tyres	Braking distance
Higher vehicle speed	Both

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