Physics U1 Test

Distance (d)

units: meters

scalar

time (t)

units: seconds

scalar

velocity (v)

units: m/s

vector

speed s(v)

units: m/s

scalar

displacement (disp.)

units: meters

vector

acceleration (a)

units: m/s²

vector

Definition of displacement

change in position (how far an object moved from a starting point and in what straight-line direction)

Example: 5 miles [East].

Definition of velocity

the rate at which position changes (how fast an object is moving and direction of that motion)

Example: 60 mph [North]

Definition of acceleration

the rate at which velocity changes (slope)

Example: 9.8 m/s² [Downward].

What defines a vector

Displacement,velocity, and acceleration are ALL vectors which include magnitude and direction.

It’s a quantity that has both magnitude and direction

What defines a scalar

have only a magnitude or size, with no direction attached

(such as time, mass, or speed)

Motion type: Standing still

v=0 m/s

a=0 m/s²

Motion type: Moving at a constant velocity

|v| > 0 m/s

a= 0 m/s²

Motion type: Speeding up

v and a both in same direction

Motion type: Slowing down

v and a in opposite direction

Motion type: Turning

a is perpendicular to v, so can happen with no change to speed

Motion graphs: d vs t graph

slope=velocity m/s

Motion graphs: v vs t graph

slope= acceleration m/s

Area under graph= displacement (m/s) (s)

Motion graphs: a vs. t graph

Area under graph= change in velocity

When velocity and acceleration are in opposite directions

object slows down

Velocity vs Time graph: Horizontal straight flat line

moving at a constant speed

flat= cruise control

Position vs time graph: Horizontal straight flat line

standing still

(flat=not moving)

Position vs time graph: curved line

speeding up/slowing down

Position vs time graph: straight sloped line (/)

constant speed

(you are changing position at a steady rate

Velocity vs Time graph: sloped line up (/)

speeding up

Velocity vs Time graph: slope line down (\)

slowing down

Constant speed Hack in word problems

object has a velocity (like 10m/s) but it just doesn’t change that velocity

Standing still hack in word problems

it stays at a velocity of 0

When velocity and acceleration are in the same direction

object speeds up

position vs. time data for an object, what type of motion must the object be undergoing?

speeding up

velocity vs time graph for an object, what type of motion

speeding up