P2.1 Motion Flashcards
Why is it difficult to measure small lengths of time or distance?
Reaction time
What can you use to measure time accurately?
Light gates where an object passes through a beam of light connected to a data logger.
How can distance be measured accurately?
Using ultrasound waves. You measure the time taken for the pulses to bounce back and then work out the distance using speed and time.
How do you calculate uniform motion speed or average speed?
Speed(m/s)=distance(m)/time(s)
Explain the difference between a vector and a scalar
Vectors have a magnitude and direction, eg force. They are represented using an arrow where the length shows the magnitude and the direction shows direction
Scalars have magnitude and no direction, eg time
What is the difference between distance and displacement?
Displacement is a vector which is the distance between the start and end point.
Distance is how much you have travelled in total
What is the difference between speed and velocity?
Speed is scalar
Velocity is a vector which has direction and magnitude.
What is acceleration?
The change in velocity per second(m/s2)
What does uniform and non uniform acceleration mean?
Uniform is when the acceleration does not change and non uniform is when it does, eg during a running race.
Acceleration formula
Acceleration(m/s2) = change in velocity(m/s)/time(s)
Change in velocity = final-initial
What does a straight line tell you in a distance time graph?
The objects speed is constant
What does a horizontal line tell you?
It s stationary
How is a light gate used to measure the speed of a falling piece of card? (4 marks)
timer starts as card enters light gate (1)
timer stops as card leaves light gate (1)
card length = distance travelled (1)
distance ÷ time taken (1)
