What is the difference between distance and displacement?
Distance is a scalar quantity whereas displacement is a vector quantity
State a typical walking speed
1.5 m/s
State a typical running speed
3 m/s
State a typical cycling speed
6 m/s
State the typical speed of sound in air
330 m/s
State the typical speed of a car on a motorway
30 m/s
Explain why an object moving with constant speed in a circular motion is accelerating
Acceleration is the rate of change of velocity.
As velocity is a vector it has both a magnitude and a direction.
As the direction of an object travelling in a circular motion is constantly changing, then the velocity is also constantly changing, which in turn means it is accelerating.
What does a horizontal line on a distance-time graph represent?
A stationary object
Distance-time graphs
What does the gradient of a line represent?
speed
(or velocity if it was a displacement-time graph)
Velocity-time graphs
What does a straight line represent?
A constant acceleration
Velocity-time graphs
What does the area under the line represent?
Displacement
Velocity-time graphs
What does the gradient of the line represent?
acceleration
HIGHERtier only
How can you determine the gradient of a curved line?
Draw a tangent to the curve at the relevant point and then determine the gradient of the tangent.
State Newton's first law of motion
When the resultant force acting on an object is zero, the forces are balanced and the object does not accelerate.
It remains stationary, or continues to move in a straight line at a constant speed.
State Newton's second law of motion
Acceleration is
- proportional to the resultant force
- inversely proportional to the mass of an object
What is meant by the inertia of an object?
How easy it is to change the velocity of an object
State Newton's third law of motion
Every force has an equal and opposite force. These:
- act on two separate bodies
- are always of the same type
What is meant by thinking distance?
The distance travelled whilst the driver reacts to a stimulus
What is meant by braking distance?
The distance travelled between the brakes first being applied and the car stopping.
What is meant by stopping distance?
The sum of the braking and thinking distances
What factor affects both thinking and braking distance?
Speed
State two factors increasing a driver's reaction time
drinking alcohol
taking some types of drugs
tiredness
being distracted
State two factors increasing a car's braking distance
wet or icy road conditions
poorly maintained brakes
worn tyres
high speed
loose gravel on the road surface
If a vehicle doubles its speed, what effect does this have on braking distance?