SP2: motion & forces Flashcards
scalar
a quantity with size/magnitude only
examples of scalar quantities
speed, mass, distance
vector
a quantity with both size and direction
examples of vector quantities
force, velocity, displacement
magnitude
the size of a physical quantity
displacement vs distance
distance: how far an object moves displacement: difference from object’s starting point to final point
what is speed?
the distance an object travels per unit of time
typical speed for walking
1.5 m/s
typical speed for running
3 m/s
typical speed for cycling
6 m/s
typical speed for cars
13-30 m/s
typical speeds for trains
50 m/s
typical speeds for aeroplanes
250 m/s
speed of sound in air
330 m/s
how to calculate average speed in a journey
total distance/total time
different ways to measure speed:
-ruler & stopwatch
-light gates (connected to timer & size of object measured with ruler)
-video analysis (distance moved from frame to frame observed on a ruler in video & time between frames)
what is the most accurate way to measure speed?
light gates
what is velocity?
speed in a given direction
what does a horizontal line on a distance-time graph represent?
stationary object
what does a sloping line show on a distance time graph?
the object is moving
what is acceleration?
the rate at which velocity changes
what is acceleration measured in?
m/s²
acceleration in freefall
10 m/s²
typical acceleration when running
2 m/s²
typical acceleration of a family car
1-7 m/s²
typical acceleration of a motorbike
1-10 m/s²
typical acceleration of a rollercoaster
30-60 m/s²
typical acceleration of a formula one car
49 m/s²
what does a sloping line mean on a velocity/time graph?
the object is accelerating
what does a horizontal line on a velocity-time graph represent?
constant velocity