P2.1 Flashcards
What apparatus is used to measure precise times e.g for a tennis ball falling?
Light gates
How do you work out speed?
Distance / Time
How many metres in a mile?
1609
How many seconds in an hour?
3600
How many orders of magnitude are between 5m/s and 123m/s
2
What is the difference between vectors and scalars?
Vectors have a magnitude and direction,but scalar only has a magnitude
If you walk in a circle at a constant speed,why does velocity change?
Velocity is vector so has a direction
If you walk in a circle you change direction,changing velocity
If you run around a stadium to where you started, what is your displacement?
0m
How do you work out velocity?
Displacement / Time
What is acceleration?
The rate of change of speed/velocity
How can you work out acceleration?
A = ( V - U ) / T
Change in velocity / time
In what situation would something have a negative acceleration?
If it is slowing down
On a distance time graph, where can you find speed?
The gradient of the graph
What does a straight line on a distance time graph mean?
The speed is constant
How do you work out velocity on a displacement time graph where there is a curve
Draw a tangent touching that point, and do change in displacement / change in time
If there is a flat line on a distance time graph, what is the speed?
0m/s
On a velocity time graph, what is the gradient equal to?
Acceleration
How do you work out displacement from a velocity time graph?
Calculate the area underneath the graph
How do you know if a graph is velocity time instead of speed time (without labels)
Velocity will have a positive and negative y axis
How do you work out the acceleration of a trolley down a ramp?
Measure the length of the trolley
Use light gates at different points at the ramp,and they will measure how long the trolley takes to pass.
Do distance / time for speed at both/all gates
For change in speed use those speeds and for time use the difference in time between light gates.
Then do change in speed / time
What is important to remember when writing units for acceleration
Its always unit squared
E.g m/s^2
What are the equations of motion?
V^2 - U^2 = 2as - most important V = U + at s = 0.5(v + u) x t S = ut + 0.5at^2 remember to rearrange when needed
What is the equation for kinetic energy?
KE = 0.5 x mass x s^2 (speed in m/s)
What is energy measured in?
Joules (J)
If you double the speed how much is kinetic energy increased by?
4 , as in the equation speed is squared
