Describing Motion

Describing Motion

Unit 4 Notes

Open Ended

How would you go about describing motion?

Motion is what

occurs when an object changes position relative to a reference point.

Two ways that we can describe motion are by

• Distance

• Displacement

Distance is

how far an object has traveled

Displacement is

distance and direction of an object's change in position from the starting point.

Practice Time

Let's see if you can determine distance vs. displacement

Multiple Choice

Bill runs 400 meters to Andy's house, turns around, and runs 400 meters back home.  What is Bill's distance?

• 0 meters
• 400 meters
• 800 meters
• 1600 meters

Multiple Choice

 Jermaine runs exactly 2 laps around a 400 meter track. What is the displacement?

• 800
• 400
• 0
• 200

Multiple Choice

A persons walks 50 meters directly north, stops, and then travels 32 meters directly south.  What is their distance traveled?

• 82 meters
• 18 meters
• 32 meters

Multiple Choice

Jerry walked from home to school, then from the school to the park. What is his total distance?

• 2 km

• 5 km

• 8 km

• 10 km

Multiple Choice

A man walks 5 miles forwards, 6 miles backwards and then 2 miles forwards. What is his displacement?

• 1 mile forward

• 13 miles

• 3 miles forward

• 1 mile

Multiple Choice

Vector quantities need both a magnitude and a _____.

• distance
• displacement
• direction
• velocity

Multiple Choice

The sum of all movements from start to the end of motion is best described as____.

• distance

• displacement

• motion

• donkey

Multiple Choice

The change in an objects position from the final position to initial position.

• displacement

• distance

• motion

• reference point

Speed is

the distance an object travels per unit of time

Is also considered to be the rate of change in a position

The formula for calculating speed is

Speed (S) = Distance (d) / Time (t)

This means: Speed (m/s) = distance (m) / time (seconds)

To calculate Average Speed you would:

take the total distance divided by the total unit of time

Comparing Types of Speed

We will now compare the three types of speed and give examples of each.

Instantaneous Speed

• Speed at any given point in time

• Driving a car and looking down at the speedometer

Average Speed is

• Total distance traveled divided by the total time traveled

• Example is taking a road trip

Constant Speed is

• Speed that does not vary

• Example: Putting the car in cruise control