Unit 1 - Kinematics

Question 1

Position-Time graphs

Answer 1

• Position-time graphs measure velocity (the slope) (V = change in d / change in t) (or rise over run)
• Position-time graphs have a direction attached to them (i.e., up, down, west, north); it is a vector quantity
• Change in position is known as displacement
• The x-axis is known as the reference point (starting point)

Question 2

P-T Graphs

What can be calculated using a P-T graph?

Answer 2

There are 3 things you can calculate using a P-T graph:

1. Constant Velocity
2. Average Velocity
3. Instantaneous Velocity

Question 3

P-T Graphs

Constant Velocity (Linear Only):

Answer 3

Use m = y2-y1/x2-x1

Treat it as a standard linear relation

Question 4

P-T Graphs

Calculating Average Velocity (Between Two Points):

Answer 4

Draw a secant* line between the two given points

Calculate the slope of it

Additionally, there is an equation for this: V_av = Δd/Δt

Question 5

P-T Graphs

Instantaneous Velocity

Answer 5

Draw a tangent* line between the two given points

Calculate the slope of it

Question 6

Velocity-Time graphs

Answer 6

• The lines on a velocity-time graph are always straight
• Velocity-time graphs measure acceleration (the slope) (a = Vf – Vi/t2 – t1) (or rise over run)
• The area underneath the line on a velocity time graph represents displacement

Question 7

V-T Graphs

What can be calculated using a V-T graph?

Answer 7

There are 2 things you can calculate using a V-T graph:

1. Acceleration
2. Displacement

Question 8

V-T Graphs

Acceleration

Answer 8

If the line is linear, calculate the slope of it

Acceleration = the slope, so find two points and calculate it!

Question 9

V-T Graphs

Displacement

Answer 9

The area underneath a line is the displacement

It may form a trapezoid (otherwise you can break it up into rectangles and triangles)

• The formula for displacement (trapezoid) is: Δd = ½ (V_i + V_f) Δt