Chapter 2: Linear Kinematics

  • Distinguish between linear, angular, and general motion
  • Define:
    • Distance and displacement
    • Average speed and average velocity
    • Instantaneous speed and velocity
  • Name units of measurement for above definitions
  • Use equations of motion for projectiles

Kinematics is the branch of dynamics concerned with the description of motion.

Data from some of the fastest races ever

Linear motion

Angular Motion

General Motion

Long Jump

Animation of linear and angular motion

Is a runner 40 m from the start or 60 m from the finish?

Where does the tighthead prop and hooker line up in rugby union?

x, y, z, rotationx, rotationy, rotationz

Slope of a position-time graph

Comparing position and velocity graphs


Marathon speed

What was a marathon runner's average speed in finishing the 42.2 km race in 2 hours 11 minutes? (Ed Eyestone)

A rowing shell was progressing across stream in the Willamette River at 8 mph relative to the water, while the river was flowing at 6 mph. What was the velocity of the shell with respect to the bank?
Pacing Example

What about changing speeds and velocities?

Mechanics of Motion App (Acceleration)

  • What combinations of velocity and acceleration are possible?

What does this imply for running around a curve?
Is someone accelerating when running a constant speed around a curve?

Shot Put Example

Slope of velocity-time graph equals acceleration

Displacement with intial velocity and with constant acceleration
d=vit + 0.5at2

Skeleton Example

A skeleton racers top speed is near 35 m/s (78 mph)
They may feel up to 5G in some turns
Velocity on entering the sled = 5.3 m/s
Acceleration on slope = 1 m/s2
  • What will the velocity be 3 seconds after entering the sled?
  • What will the displacement 3 seconds after entering the sled?


What is the average speed if you swim 1500m at 1.46 m/s, bike 40 km at 11.27 m/s, and run 10 km at 5.72 m/s? (2012 Olympic Triathlon)