Unit I - Mechanics - Study of the relationship between force and motion

I. Kinematics - Mathematical methods of describing and predicting motion

We can describe and predict the motion of objects with:

Motion Diagrams

(plots of motion information)

• equations

II. How do we describe motion?

Acceleration

Velocity

(speed and direction)

III. What do we measure when we study motion?

Distance (meter ≈ 1 yard)

Time (seconds)

Direction

A.  Speed - how much distance an object covers per unit time

1. Speed = distance / time

a) Units - m/s, km/hour, miles/hour

Ex 1) An object travels 5 meters in 2 seconds. Find its speed.

Answer: Speed = d/t

= 5m/2 sec

= 2.5 m/s

Ex 2) An object moves at a rate of
3 m/s for 1.5 seconds. How far did the object move?

Answer: Speed = d/t

3 m/s = d/1.5 sec  

d = 4.5 m 

Photos made by Eadweard Muybridge (1830- 1904)
Animation by User Waugsberg

Public Domain

Ex 3) An object moves at rate of 4 m/s over a distance of 10 meters.

How long did it travel.

Answer: Speed = d/t

4 m/s = 10 m/t

(4 m/s)t = 10 m

t = 2.5 seconds

Displacement