Physics
Ch. 2 Study Guide
Test Date: 9/22/15
Know the definitions and be able to provide examples (if applicable) for the following terms:
- coordinate system
- displacement
- average velocity
- distance
- average speed
- slope
Be able to apply the following formulas:
Distance = sum of paths traveled
Displacement:
Average speed = distance/time
Average velocity:
⃑ = ∆𝑥 = 𝑥𝑓 − 𝑥𝑖
𝐷
𝑣𝑎𝑣 =
Position- time equation for motion:
∆𝑥 𝑥𝑓 − 𝑥𝑖
=
∆𝑡
𝑡𝑓 − 𝑡𝑖
𝑥𝑓 = 𝑥𝑖 + 𝑣𝑡
Be able to do the following:
- Be able to differentiate between scalar and vector measurements
- Use the correct SI units for distance, displacement, speed, and velocity
- Be able to identify average velocity as positive or negative depending on sign of displacement
- Be able to create and gather data from a position-time graph.
- Remember that slope = average velocity
Practice problems:
Answers are on the next page.
1. A physics book is moved once around the perimeter of a table of dimensions 1.0 m by 2.0 m.
a. What is the distance traveled?
b. If the book ends up at its initial position, what is its displacement?
2. What is the displacement of the cross-country team if they begin at the school, run 10 miles and
finish back at the school?
3. In the 2008 Olympics, Jamaican sprinter Usain Bolt shocked the world as he ran the 100-meter dash
in 9.69 seconds. Determine Usain's average speed for the race.
4. In last week's football game, Al Whatshisname, the star halfback of Serra's football team, broke a
tackle at the line of scrimmage and darted upfield untouched. He averaged 9.8 m/s for an 80-yard
(73 m) score. Determine the time for Al to run from the line of scrimmage to the end zone.
5. A high school athlete runs 1.00 x 102 m in 12.0 s.
a. What is the velocity in m/s?
b. In km/h? 3-1
6. A person walks 13 km in 2.0 h.
a. What is the average velocity in km/h?
b. In m/s? 3-2
7. A train leaves the station at the 0.0-m marker traveling with constant velocity at 36.0 m/s.
a. How many seconds later will the train pass the 1620.0-m marker?
b. What is the velocity of the train in km/h? 3-6
8. At 1:00 pm, a car, traveling at a constant velocity of 94 m/h toward the west is 17 km to the west of
your school. Where will it be at 3:30 pm? (Hint: you’re looking for final position.) 3-7
9. Cleo the black lab runs to pick up a stick on the ground at the location x = 3.0 m. The equations of
motion for Cleo is x = -12.1 m + (5.2 m/s)t.
a. Where is Cleo a t = 1.6 s?
b. At what time does Cleo reach the stick?
10. Two dragon flies have the following equations of motion:
x1 = 2.2 m + (0.75 m/s)t
x2 = -3.1 m + (-1.1 m/s)t
Which dragonfly is moving faster? Explain your answer.
11. What is the final position of an object that starts at 7.3 m and moves with a velocity of -1.1 m/s for
3.5s?
Answers to practice problems:
1. a) 6.0 m; b) 0 m
2. 0 miles
3. 10.3 m/s
4. 7.5 s
5. a) 8.20 m/s; b) 29.5 km/h
6. a) 6.5 km/h; b) 1.8 m/s
7. a) 45.0 s; b) 130 km/h
8. 252 km west of school
9. a) -3.8 m; b) 2.9 s
10. The second dragon fly is faster- the magnitude of his velocity (-1.1 m/s) is greater than the
magnitude of the first dragon fly’s velocity.
11. 3.5 m
Classroom practice problems from 11/22/13
DISTANCE & DISPLACEMENT
Calculate the distance and displacement in each problem.
1. David walks 3 km north and the turns east and walks 4 km.
2. Amy runs 2 miles south, then turns around and runs 3 miles north.
3. Jermaine runs exactly 2 laps around a 400-meter track.
4. Eric crawls 4 feet south, then turns east and crawls 6 ft.
5. Ray runs 8 m north, 8 m west, and 8 m south.
VELOCITY & SPEED
6. What is the velocity in m/s of a car that traveled a total of 75 kilometers north in 1.5 hours?
7. What is the velocity of a plane that traveled 3000 miles from New York to California in 5
hours?
8. John took 45 min to bicycle to his grandmother’s house, a total of 4.0 km. What was his
speed in km/h?
9. It took 3.5 h for a train to travel the distance between two cities at a speed of 120 mi/h.
How many miles lie between the two cities?
10. How long would it take for a car to travel a distance of 200 km if it is traveling at a speed of
55 m/h?
11. An ant carries food at a speed of 1 cm/s. How long will it take (in seconds) for the ant to
carry a cookie crumb from the kitchen table to the anthill, a distance of 50 m?
Answers:
1. Dist = 7 km; displacement = 5 km northeast
2. Dist = 5 mi; displacement = 1 mi north or -1
m
3. Dist = 800 m; displacement = 0 m
4. Dist = 10 ft; displacement = 7 ft southeast
5. Dist = 24 m; displacement = 8 m west or -8
m
6. 14 m/s north
7. 600 mi/h west
8. 5.3 km/h
9. 420 mi
10. 4000 h
11. 5000 s