1.1.2 part one Chapter 11.2 Velocity
Speed - ratio of the distance an object moves to the amount of time the object moves (m/s) (p. 332)
Car might travel 80 km/hr
Instantaneous speed - rate at which an object is moving at a given moment in time (i.e. speed of your car might be 55 km/hr)
Constant speed - speed that does not vary (i.e. setting your cruise control to 55 mph)
Average speed - total distance traveled divided by total time of travel (i.e. how fast something moves for an entire trip --- marathon runner who starts off fast and then slows down) (p. 333)
To calculate average speed: d = distance
v = speedt = time
d = v x t or v = d/tort = d/v
Graphing motion:
Plotted as Distance (m) on the y axis vs. Time (s) on the x axis
Slope = speed
Slope = rise over run
- Refer to graphs on p. 334
- Need to know how to interpret motion using graphs
- Steeper the slope = constant high speed
- Flat lines represent when the object is stopped
- Speed = rise/run
- Rise = 0
- Therefore, the speed equals 0
Velocity - speed AND direction of an object (p. 336)
- Does a car going around a curve have a constant velocity?
- Does a car when it slows down at a stoplight have a constant velocity?
Samples:
1. What is the average speed of a cheetah that sprints 100 m in 4 seconds?
2. A car moved at an average speed of 60 km/hr. At this rate, how far did it travel in 4 hours?
3. Austin drove for 3 hours to see his friend in West Palm Beach. The drive was 197 miles, what was his speed?
4. Timothy walked at a rate of 5m/s, how long did it take for him to walk 230 meters?
5. Is a fine for speeding based on average or instantaneous speed? Why?
6. Chris runs the 100m dash with an average speed of 8.2 m/s, what was his time?
7. Nicole rode her bike around the track twice. She rode a total of 880 m and it took her 90 seconds to do so, what is her speed?
8. The graph describes the movement of a car in the Oyster Roaster Roller Coaster Ride. Which is the best interpretation of the graph?
A. the car moved at a constant velocity throughout the ride.
B. the car’s velocity was slowest at 1st then fastest at the end.
C. the car’s velocity shows that it never accelerated.
D. the car’s velocity was fastest at 1st and slowest at the end.
9. In order to determine the speed of an object, what measurements must be made?
A. distance & direction B. distance & mass
C. time, distance, & volume D. distance & time
10. Large planes travel at an average velocity of 50m/s. It takes 20s from them to lift off the ground. What is the minimum length an airport runway should be to ensure safety?
A. at least 10,000m b. at least 5,000m
c. at least 1,500m d. at least 1,000m
11. Circle the graph that best represents an object experiencing positive acceleration?
12. What was the average speed of this object between 2 to 4 seconds?
A.1.5m/s b. 0.5m/s
c. 0.75m/s d. cannot be determined
13. Based on the table below, what conclusion can be made about the velocity of this falling object?
A. it is constant for all 4s. b. it decreases over time.
C. it increases every second
d. it is not related to acceleration.
ACCELERATION DUE TO GRAVITY
TIME / VELOCITY1s / 9.8 m/s
2s / 19.6 m/s
3s / 29.4 m/s
4s / 39.2 m/s
14. If a clap of thunder is detected 5s after lightning struck 1,750m away, what was the velocity of the sound waves?
A. 216m/s b. 350m/sc. 1,745 m/sd. 8750m/s
15. Lindsay has a stopwatch, a compass, and a meter stick. What can she calculate using all three of the tools?
A. volume b. density c. speed d. velocity
16. An unbalanced force propels a car to move 300km in 4hrs. What is the average speed of the car?
17. George, Steve and Demond each race a remote control soapbox car on a straight, 2m course. George’s car completes the race in 10s. Steve’s car completes the race in 13s. Demond’s car completes the race in 8s. Which of the following is the correct value of the average velocity of the fastest car?
A. 20m/s b. 26m/s c. 16m/s d. 0.25 m/s
18. In order to determine the velocity of an object, what measurements must be made?
A. time and distance
b. time, distance and mass
c. time, distance and direction
d. time, distance and volume
19. Ashley navigates her kayak down a stretch of Goose Creek in 0.25hr. Her rate of speed over the course of the trip is 8km/h. How far has she traveled?
20. Calculate the rate for the following three scenarios and note whether they are speed or velocity.
(1.) Taijae drives 400km in 5h.
(2.) Ekia hang glides down a 3000m mountain in 30min.
(3.) Logan swims 100m in 50s.
21. Which best describes the difference b/w speed and velocity?
A Speed includes distance & direction while velocity only includes distance.
B. Speed includes distance & direction while velocity only includes direction.
C. Velocity includes distance & direction while speed only includes direction.
D. Velocity includes distance & direction while speed only includes distance.
22. Sound travels at a speed of 330m/s. If Deshawn hears a police siren 165m away, how long did it take for the sound to travel from the police siren to his ear?
23. Which best describes the definition of speed?
A Speed is the same as velocity.
B. Speed is the distance traveled.
C. The distance traveled is not a factor in determining speed.
D. Speed is the distance traveled per unit of time.