PHYSICS 20N UNIT 1 PROBLEM REVIEW A

NAME:

BE SURE TO SHOW EXPLICIT FORMULAS AND SUBSTITUTIONS FOR ALL QUESTIONS, WHERE APPROPRIATE. ROUND FINAL ANSWERS CORRECTLY; GIVE CORRECT UNITS AND DIRECTIONS FOR VECTORS. This unit contains considerable content – knowledge of physics, terms, etc. – that is not covered by this review. Be sure to review the text, quizzes, and your notes in preparation for the unit exam. 1. Calculate each of the following; round answers correctly. a)

16.1 + 84 - 1 = _________________

c)

(7.3)(43.5)(0.01) = _________________

b) 24 pencils divided into 2 boxes d) (3.4 x 10-3)÷(6.7 x 10-2) = _______________ _________________ 2. Convert each of the following. a)

1.20 cm = _________________ m

b) 0.0346 dN = _________________ daN

c)

4500 W = _________________ mW

d) 245 km/h = _________________ m/s

3. Write in opposite (scientific or positional) notation. a)

1.9 x 10-3 = _________________

b) 6.0 x 105 = _________________

c)

0.000 86 = _________________

d) 165 700 = _________________

4. A girl walks 4.0 km east in 2.0 h, then 2.0 km west in 0.5 h, and finally 8.0 km east in 2.1 h. Draw a vector sketch showing her motion. Find her average speed (distance divided by time) and average velocity (displacement divided by time – direction is the same as that of the displacement.)

___________________________ ___________________________ 5. A dog runs at 4.0 m/s a distance 20 m east, then turns and runs at the same speed north for 4.0 additional seconds. Find the dog’s final displacement (magnitude and direction) and average velocity (magnitude and direction) for the run.

___________________________ ___________________________ 6. A man walks from the front to the rear of a boat at a speed of 2.0 m/s with respect to the boat; the boat is moving south along a river at 8.0 m/s. What is the apparent velocity of the man as seen by a man standing on the bank of the river? ___________________________

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7. A student moves on a straight sidewalk from one school to an adjacent one; she then turns and walks partway back to the first school. School B is straight east of school A and the student starts at school A. The graph below shows the motion of the student.

36 30

x (m)

24 18 12 6.0 0

10

20

30

40

50

60

70

80

90

t (s)

a) Find the student's velocity at t = 10 s, at t = 25 s, at t = 50 s, and at t = 68 s. Show any needed constructions. ___________________________ ___________________________ ___________________________ ___________________________ b) Could this graph be taken from actual data? Explain. c) How far apart are the two schools? ___________________________ 8. A boy on a wagon starts down a hill 90 m long with an initial velocity of 1.3 m/s, reaching the bottom of the hill in 24 s. Calculate his (assumed uniform) acceleration and his velocity at the bottom of the hill.

___________________________ ___________________________ 9. A boy drops a stone off a bridge; the stone hits the water below 1.95 s later. a)

How high is the bridge?

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b) What is the stone's speed just before it hits the water?

___________________________ 10. The graph shows an object moving along an east-west path. a) Use graphical techniques to determine the acceleration of the object between 0 – 1 s; between 4 – 6 s. SHOW YOUR METHOD ON THE GRAPH.

2.0 v (m/s)

___________________________

4.0

___________________________ b) Use graphical techniques to determine the displacement of the object from 0 – 2 s. SHOW YOUR METHOD ON THE GRAPH.

0

2

1

3

4

5

6 t (s)

-2.0

-4.0

___________________________ c) At what time does this object change direction? How do you know? ___________________________ 11. A train traveling at 40 m/s slows with a uniform deceleration of –0.60 m/s2. Find how long it takes to stop, and how far it travels while stopping.

___________________________ ___________________________ 12. Sketch the east-west motion described below on the graph. Movements are at constant speed.     

Starting at zero, moves east a distance of 10 m in 3 s Moves at 5 m/s east for 2 s Stops for 3 s Moves west at 10 m/s for 4 s Returns to starting point in 3 s

40

20

x 0

5

10

15

-20

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t

13. The sketch shows two cyclists riding along an east-west cycle path. a)

400

How much later does Cyclist B begin riding than Cyclist A? _________________________

300

c)

At what time does Cyclist B overtake Cyclist A? _________________________

d) Find the velocity of each cyclist.

d (m)

b) Do the cyclists start at the same point?

200

100

Cyclist A

_________________________

Cyclist B

_________________________ e)

0

After 110 s, how far apart are the two cyclists?

25

50

75

100

_________________________ 14. A man standing on the roof of a 15.0 m high building throws a tennis ball horizontally; the ball lands on the parking lot below, 12.0 m from the base of the building. a) How long did the ball take to land?

____________________________ b) How fast did he throw the ball?

____________________________ c) What was the final velocity of the ball just before it struck the ground? Give magnitude and direction from the vertical; note that this velocity is the vector sum of the horizontal and vertical velocities.

____________________________

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15. An ant walks 2.50 m north, then 4.00 m west. Find the displacement of the ant relative to his starting point. Give magnitude and a standard position direction – include a vector diagram.

___________________________ 16. Two small planes set off on a flight from Centerville to Amdill; Amdill is 240 km due north of Centerville. Each plane has an airspeed of 220 km/h. A wind blows from the west at 60.0 km/h. If the pilot of the first plane flies with the plane pointing due north, what is his ground velocity? Include a vector sketch; give magnitude and direction as a standard position angle.

___________________________

17. Find the x and y-components of a displacement of 750 km in a direction of 320˚.

____________________________ ____________________________

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18. A ball rolled across a table at a constant speed of 0.425 m/s. It flew off the end of the table. The table top was 1.33 m above the floor. How far from the base of the table did the ball land?

19. a) An archer shot an arrow at an angle of 34.2º. The arrow left the bowstring travelling with an initial velocity of 36.8 m/s and flew until it landed. Assuming the ground was perfectly flat, how far away did it land?

b) What was the maximum height reached by the arrow?

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NUMERICAL ANSWERS 1. a) 99 b) 12 c) 3 d) 5.1 x 10-2 2. a) 0.0120 b) 3.46 x 10-4 c) 4.500 x 106 d) 68.1 3. a) 0.0019 b) 600 000 c) 8.6 x 10-4 d) 1.657 x 105 4. 3.0 km/h; 2.2 km/h east 5. 26 m at 39˚ 2.8 m/s at 39˚

9. a) 18.7 m b) 19.1 m/s 10. a) 4.0 m/s2 east; 1.0 m/s2 east b) 6 m c) 2.5 s 11. 67 s; 1.3 km 13. a) b) c) d) e)

35 s yes 70 s 2.6 m/s east; 5.1 m/s east 100 m

14. a) 1.75 s b) 6.86 m/s c) 18.5 m/s at 21.8˚ from vertical 15. 4.72 m at 148˚

6. 6.0 m/s south 16. a) 228 km/h at 74.7˚ 7. a) t = 10s: 0.5 m/s t = 25 s: 1.2 m/s t = 50 s: 0 t = 68 s: -0.8 m/s b) Yes c) 36 m 8. -0.20 m/s2; -6.2 m/s

PHYSICS 20 N UNIT 1 REVIEW

17. 575 km; –482 km 18. 0.221 m 19. a) 128 m b) 21.8 m

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