Physics - speed, distance and time Flashcards
What is a vector?
A measurement having size (magnitude) and direction, eg a displacement of 4 m North
What is a scalar?
A quantity that requires only a size(magnitude), for example, distance travelled is 20 m.
What is velocity?
A speed in a direction
What is displacement?
Displacement is the distance moved in a straight line, or a given direction from the starting point. eg 50 km due north of the original position.
What are some examples of scalar measurements?
distance
speed
time
What are some examples of vector measurements?
displacement
velocity
acceleration
force
momentum
What is acceleration?
The change in velocity per second
How do you work out stopping distance?
The total distance needed by a car to stop. Stopping distance = thinking distance + braking distance.
What is thinking distance?
Distance travelled between reacting to a danger or a reason to stop the vehicle and braking.
What is braking distance?
Distance travelled while braking.
What factors can affect thinking distance?
speed
distractions, eg mobile phones
alcohol
drugs
tiredness
visibility
What factors can affect braking distance?
speed
worn brakes
wet road
mass of the car
worn tyres
icy road
What is reaction time?
Time taken between seeing an event and reacting to it.
How do car safety features make collisions less fatal?
The safety features won’t change the mass of the car or the starting and end speeds, but do increase the impact time t in the formula. As impact time increases, the force on the occupants gets less as you are dividing by a higher value.
What are some car safety features?
air bags
crumple zone
inertia wheel safety belts
