Motion

Speed, Velocity, and Acceleration

Question

When can you determine how fast you are going in a jet plane?

Frames of Reference The object or point from which

movement is determined Movement is relative to an object

that appears stationary Earth is the most common frame

of reference

Questions

What is the frame of reference for the sunset?

What is a frame of reference?

What is the most common frame of reference?

Motion IN: What is motion? Motion is a change in position

relative to a frame of reference Speed is the distance traveled

in a given amount of time Speed=distance time

Speed

The units for speed: meters/second (m/sec) kilometers/hour (km/hr) Speed that does not change

is constant speed

Average speed

Total distance divided by the total time

Formula: Total distance total time

Velocity Speed in a given direction Velocities in the same direction

combine by adding Velocities in different

directions combine by subtracting

Interesting fact Why is direction important? Rockets are launched in the same direction of the earth’s rotation to get an extra boost of 1800 km/hr to its speed

Questions What is motion? What is speed? How is it calculated?

What is average speed?

Questions

How is velocity different from speed?

Which two factors determine an object’s velocity?

The Speed Triangle

Distance

Time Speed

Triangle Explained

Distance = Time X Speed Time = Distance/Speed Speed = Distance/Time

Problems to Solve

1. If Steve throws the football 50 kilometers (km) in 3 hours, what is the average speed of the football?

2. If it takes Ashley 3 seconds to run from the batters box to first base at an average speed of 6.5 meters per second, what is the distance she covers in that time?

Answers for Questions 1-2

1. Distance = 50km Time = 3 hr

Speed = distance/time or 50km/3hr

Answer is 16.7km/hr

2. Time = 3 sec Avg Speed = 6.5m/s

Distance = time X speed or 3s X 6.5m/s

Answer is 19.5m

More Problems3. Lauren’s SUV was detected exceeding the

posted speed limit of 60 kilometers per hour, how many kilometers per hour would she have been traveling over the limit if she had covered a distance of 10 kilometers in 5 minutes?

4. Tina’s calculations of the tarantula found that the spider was able to cover 20 centimeters in 5 seconds, what was the average speed of the spider?

Even More Problems

5. Mike rides his motorcycle at an average speed (velocity) of 20 meters/second for 500 seconds, how far did he ride?

6. Sarah backstrokes at an average speed of 8 meters per second, how long will it take her to complete the race of 200 meters length?

Some real life speed problems7. How much time would it take for the

sound of thunder to travel 2000 meters if sound travels at the speed of 330 meters per second?

8. How much time would it take for an airplane to reach its destination if it traveled at an average speed of 790 km/hr for a distance of 5000 kilometers?

9. An ant can travel approximately 30 meters per minute. How many meters could an ant move in 1 hour (60 minutes)?

Resultant Velocity

Velocities in the same direction combine by adding

Velocities in different directions combine by subtracting

Acceleration The change in velocity Acceleration is measured in

m/sec/sec or m/sec2

Formula is: (final velocity - original

velocity)/time

Deceleration vs. Acceleration A decrease in velocity is

deceleration or negative acceleration

A distance-time graph for acceleration is always a curve

Questions What is acceleration? What is the shape of a

distance-time graph for acceleration?

What is centripetal acceleration?

Graphing Bell Work

Person A and B are running a race.

Which line has a greater slope, A or B?

Who won the race and ran faster than the other person?

How do you know this line has a greater slope

What evidence shows this person ran faster than the other person?

Practice Graph

Can you figure out the speed for Point:

A

B

C

D

E

What is happening to the motion between point C and D?

What is happening to the motion between point D and E?

Graph for running “The Mile” in P.E.

Why is the blue line curved?

If something is getting faster or slower what vocabulary word do we use?

The green line represents what type of speed?

“The Mile” continued Can you figure out what

might have happened to the student represented by the red line?

Include what is happening to the time and distance as the red line is changing.

Newton’s Laws

The Three Laws of Motion

Momentum Momentum is equal to the mass of an object times its velocity

momentum= mass x velocity

Conserving Momentum The law of conservation of momentum states that the total momentum is NOT lost, only transferred

Questions What is momentum? What happens to momentum

as the mass of a moving object increases?

What is the formula for momentum?

What is the law of conservation of momentum?