KINEMATIC KONCEPTS

Motion

A change in position over time with respect to a reference point.

Scalar vs. Vector Quantities

Time Temperature Mass

Vector, the villain Force Velocity Acceleration

Scalar: Magnitude onlyVector: Magnitude and Direction

CFU #1: Sort these into Scalar and Vector quantities.

0. 5 meters 30 m/sec, East 5 mi., North 20 degrees

Celsius 256 bytes 4000 Calories

Scalar 0.5 meters 20 degrees

Celsius 256 bytes 4000 Calories

Vector 30 m/sec, East 5 mi., North

Distance vs. Displacement

Distance: total length travelled

Displacement: Change in position

CFU#2 Distance vs. Displacement A car moves 65

km due East, then 45 km due West. A. What distance

was travelled? B. What is the

total displacement?

Answer: A. Distance =

110. km B. Displacement

= 20. km, due East.

65 km

45 km20 km

CFU#3 Distance vs. DisplacementBelow is the graph of the position of a quadcopter over time. The positive direction is above the ground. A. What distance does

the quadcopter travel in the 7 seconds?

Answer: 1.3 meters (0.8 meters up plus 0.5 meters down)B. What is the position of

the quadcopter after 7 seconds?

Answer: 0.5 m above the ground.C. What is the

displacement of the quadcopter in the 7 seconds?

Answer: 0.3 meters, up (It began 0.2 meters above the ground and ended 0.5 meters above the ground.)

Average Speed: a scalar quantity

typical units are m/s or km/h Basic problem solving steps:

ID givens and unknown List and label, including units Check units. Convert if necessary. ID needed equation. Add to list. Isolate unknown in equation. Plug in and solve. Remember units and SF

distance

speed time

Practice Problem

You ride your bike for 30. minutes at an average speed of 15 km/h. How far did you go?

CFU#4-7

Solve the problems on your paper, making sure to follow the problem solving tips.

Answers: 4. 71 km/h 5. 0.60 h 6. 61 m or .061 km 7. a. 2.2 h b. 4.0 h c. 55 km/h

d. 0!!

distance

speed time

Avg. Speed vs. Avg. Velocity

or This is a vector

quantity. This is what we have

been solving when we find slope on a position vs. time graph

Speed: distance per timeVelocity: displacement per time

This is a scalar quantity

Avg. Speed vs. Avg. Velocity

Your textbook does not make a distinction between average speed and average velocity, although there is a difference. It will always say average velocity.

We will explore the subtle differences between average speed and velocity a little later… Δd or Δx

v Δt

CFU #8

A cyclist maintains a constant velocity of +5.0 m/s. Make a table showing the position of the

cyclist every 10.0s for 60.0s (start at 0.0, 0.0)

At time t = 0.0, the cyclist is +250 m from point A. How might you show this on a graph? Δd or Δx

v Δt

vs.

Remember this problem? (CFU #2) A car moves 65 km due East, then 45 km

due West. The distance travelled was 110. km, and the

displacement was 20. km, East. CFU #9 If the trip took 2.5 hours, what is

the average speed? What is the average velocity? Answer: avg. speed = 44 km/hr, v = 8.0 km/hr,

East

vs.

Remember this problem? (CFU #3)

CFU #10 Calculate the average speed and average velocity for the quadcopter.Answers: Average Speed = (1.3 m/7 sec) = 0 .19 m/s = 0.2

m/sAverage Velocity = (0.3m/7 sec) = 0.04 m/s, Up

Hi-Lo: A game of average speed and average velocity

Everyone starts at 0 on the gameboard (2 metersticks) Positive displacements are to the right, negative to the

left. For each turn, roll a 4-sided die and a 6-sided die.

4-sided die represents the magnitude of your displacement in 10 km increments. 6-sided die represents the direction of your displacement: evens are positive, odds are

negative.

Move your game piece the indicated displacement (cms represent kms)and record your move in the table. Then compute the rest of the columns in the table, and plot your position on the position vs. time graph.

Each turn represents one hour of time. At the end of the game, the winner has the greatest

difference between the magnitudes of their average speed and their average velocity.