Physics CPA Unit 2 1-Dimensional Kinematics

Physics CPA Unit 2 1-Dimensional Kinematics

Concept Questions

1.  What is the importance of a frame of reference when studying the motion of an object? Use an example.

2.  Your car odometer measures distance traveled. Your tires will wear as this distance increases; there is no such thing as “negative” tire wear. However, change in position, or displacement, can be either a positive or a negative value. Explain.

3.  You jog one time around the track. What is your average velocity? Explain how this can be true, yet you feel tired.

4.  What two controls on a car cause a change in speed? What control causes only a change in velocity?

5.  In drag racing, is it possible for the car with the greatest speed crossing the finish line to lose the race? Explain, use numbers in your explanation.

6.  What quantity describes how quickly you change how fast you are traveling or how quickly you change your direction? What is required to cause this change?

7.  A ball is tossed upward with velocity ‘v’.

a)  What is the change in velocity each second on the way up?

b)  What is the change in velocity each second on the way down?

c)  What is the velocity at the maximum height?

d)  What determines the maximum height?

e)  What is the acceleration on the way up, at the top, and on the way down?

f)  What is the velocity of the ball when it returns to it’s launch position?

8.  What quantity is represented by the slope of a

a)  Distance vs. time curve?

b)  Position vs. time curve?

c)  Velocity vs. time curve?

9.  Sketch qualitative position vs. time curves for each motion described:

a)  Constant positive velocity

b)  Object stays at rest

c)  Velocity increases

d)  Steady velocity, then slows to a stop

10. Runner A and Runner B both run a constant speed.

Runner A is slower than Runner B, and gets a head start, beginning at t=0. Runner B starts later (‘t’) but, being faster, passes Runner A at some time > 2t.

-Sketch a qualitative position vs. time graph with curves for runner a and runner B.

-Label the curves, and the times indicated.

Problems

Constant Velocity

11. A bird can fly at a rate of 25 km/hr. How long does it take to fly 15 km?

12. Light travels at the rate of 3.0 x 108 m/s in space. If light from the sun takes 8.3 minutes to reach the earth, what is the Earth-sun distance?

13. If the average distance from the sun to Saturn is 1.4335 x 109 km, how long does it take for sunlight to reach Saturn, on average?

14. A car is moving at a constant speed of 30 m/s. A ball rolls into the street and the driver takes 0.75 s to fully apply the brakes and start slowing down. Calculate the distance traveled by the car before it even begins to slow.

15. On a trip, you drive at 65 mph for 130 miles. It begins to rain, so for the rest of the trip you drive at 55 mph. The total time for the trip is 3 hours and 20 minutes.

a)  Determine the total distance traveled.

b)  Calculate the average speed for the entire trip.

Acceleration

16. A car is advertised to be able to accelerate at a rate of 1.6 m/s2 . How long would this car take to accelerate from 22 m/s to 31 m/s?

17. An airplane accelerates from rest at a rate of 4.0 m/s2. If the plane takes 40.0 s to reach takeoff speed, what is the plane’s takeoff speed?

18. Leaving the freeway, a car slows from 25 m/s to 8 m/s at a constant rate of 2.1 m/s2. How long does it take for the car to slow down at this rate?

19. In braking to a stop, a car leaves skid marks 80.0 m long on the highway. Assuming a braking acceleration of -7.00m/s2, calculate the velocity of the car at the start of the braking

20. A car brakes to a stop from a speed of 25.0 m/s in 5.0 s. How far does the car travel during this time?

21. A pop-up is hit straight up into the air with an initial speed off the bat of 25 m/s.

How high does the ball go?

22. The world record vertical leap is 60 inches, which is 1.52 meters. (This beats the best NBA leapers by a foot.) Calculate the “hang time” of this world record leaper, which of course includes the time “up” and the time “down”.

Book:

Pg. 69 # 28, 29

Pg. 71 # 30, 32, 34

Pg. 82 # 88, 90

Pg. 74 # 42-45

Pg. 82 #98-101

(Some entries adapted from Physics, Principles and Problems, Zitzewtz, et al; Glencoe/McGraw Hill, 2005 and Physics, Walker; Prentice Hall, 2002; and Physics, Giancoli, Prentice Hall, 2002 and Conceptual Physics, Hewitt; Prentice Hall, 2006)

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