Motion

An object is in motion if the distance from another object is changing.

A reference point is the starting point you choose to describe the location, or position of an object.

Position is an object’s distance and direction from a reference point.

Describing Motion

Think Pair Share – Describe how you would get to the bakery.

Displacement is the distance between the starting point and finish point.

Distance is the length traveled.

Distance vs. Displacement

Constant Speed = speed stays the same

Instantaneous Speed = speed at a specific instant in time.

Speed changes when you: slow downspeed up stop

Speed

Velocity is the speed AND direction of a moving object.

Velocity changes when: speed changesdirection changes

both change

Velocity

Think Pair Share – Explain this diagram.

Think Pair Share – Differentiate between speed and velocity.

Acceleration is a change in velocity during a period of time.

Acceleration changes due to a change in speed or a change in direction.

Negative acceleration = slowing down

Positive acceleration = speeding up

Acceleration

Speed = Distance Time

Average Speed = Total DistanceTotal Time

Distance = Speed X Time

Time = Distance Speed

Speed & Velocity Formulas

An easy way to solve problems

D

S T

An eagle flies 300 m in 12 s, what was its average speed?

Speed = distance/time

Speed = 300m/12 s

Speed = 25 m/s

Example

1. A mail truck takes 20 s to move between mailboxes that are 10 m apart. What is the average speed of the mail truck?

2. Sound travels 330 m/s. You hear the sound of the bat hitting a home run 0.5 s after you see it. How far away are you?

Practice Problems

3. Two cities are 250 km apart. How much time will it take to travel from one city to the other at 100 km/h?

4. If a train travels 120 km at 30 km/h, how long will it travel?

5. Steve swims 10 m in 20 s. What is his average speed?