P2 - Forces Flashcards
How to measure the distance?
Use a ruler
How to measure time?
Use a stopwatch
For accuracy - use light gates
What is a accurate way to measure distance and how does it work?
Ultrasound
There is a motion sensor that emits ultrasound wave.
It times how long it takes for the pulse to travel to an object and back again.
Use the distance = speed * time to calculate distance
What is uniform motion?
Speed does not change
Distance (m) = speed (m/s) * time (s)
What is non uniform motion?
Speed changes
Average speed (m/s) = total distance (m) / total time (s)
How to convert miles into metres?
1 mile = 1609 metres
What is a vector?
Quantity that has direction and magnitude
E.g. forces
Length of the arrow tells the magnitude and direction that the arrowhead points is the direction
What is a scalar?
Has a magnitude but no direction
E.g. time
What is distance?
How far you’ve travelled (scalar quantity)
What is displacement?
Distance from a point in a particular direction (vector quantity)
What is speed?
How fast something is going (scalar)
What is velocity?
How far something’s going in a given direction (vector)
What is the formula for acceleration?
Acceleration (m/s^2) = change in velocity (m/s) / time (s)
What is the acceleration due to gravity on earth?
9.81 m/s^2
What does a graph of distance against time mean?
Tells you the speed of an object on its journey
Horizontal line - stationary , not moving
Diagonal line - object moving at steady speed
Curved line - moving at changing speed
How to work out speed in distance - time graph?
Gradient of the line
Difference in distance / distance in time
What is a contact and non contact force?
Contact force is two objects that must be touching e.g. friction
Non contact forces are forces between two objects that aren’t touching
E.g. magnetic
What is meant by the term interaction pair?
Pair of equal and opposite forces acting on two different objects.
