PHYS 201 TEST #1 9/14/11 Dr. Holmes NAME:

DO ALL EIGHT PROBLEMS. THE WORTH OF EACH PART OF EACH PROBLEM IS MARKED NEXT TO THE SLOT FOR THE ANSWER. SHOW YOUR WORK FOR PARTIAL CREDIT.

1) a) What is your height in feet and inches?

b) What is it in centimeters?

c) Express 24 in² in cm²:

154.8 cm²

2) What angle does the sun make when viewed from Venus given that the diameter of the sun is 1.4 million km and the distance from Venus to the sun is 108 million km?

a) degrees: 0.743^o;

b) radians 0.013 radians;

c) in revolutions: 0.00206 revs

d) As seen from the earth, the sun makes an angle of 0.5^o . Would the sun appear to make a smaller, the same, or bigger angle when viewed from Venus compared to when it is viewed from the earth? (Venus is closer to the sun than the Earth.)

Bigger angle.

3) a) Convert the following vector (-15 cm, +24 cm) from rectangular to polar form:

(28.3 cm, +122.0^o)

 b) Convert the following vector: (42 m, -34°) from polar to rectangular form:

(34.82 m, -23.5 m)

4) Add the following three vectors and express your answer in POLAR form:

A = (47 m, 17°)

B = (52 m, 299°)

C = (23 m, 152°)

(54.1 m, -22.8^o)

Draw a quick picture showing vectors A, B, and C; also show the resultant vector and label it R:

 5) A runner runs a 10 kilometer race in 40 minutes even.

What is the person’s average velocity during that time:

a) in miles/hour:

9.33 mph.

b) in m/s:

4.17 m/s.

c) At this average speed, how long would it take the runner to run 1 mile?

0.107 hours = 6.43 minutes = 6 minutes 26 seconds

d) At this average speed, how long would it take the runner to run a marathon (26.3 miles)?

2.819 hours = 2 hours, 49 minutes, 8 seconds.

6) To the right is a graph of v(t). On the graphs below it, sketch x(t) and a(t) assuming that x_o< 0.

7) Given the following velocity data:

v(0 sec.) = 2 m/s

v(1 sec.) = 3 m/s

v(2 sec.) = 1 m/s

v(3 sec.) = -4 m/s

and given that x_o = +3 meters;

a) What is the average acceleration between t = 2 seconds and t = 3 seconds?

-5 m/s²;

b) What is the position at t = 3 seconds?

6.0 meters.

8) An airplane takes off from an aircraft carrier. Assume the following: the airplane undergoes constant acceleration during the take-off. The distance for take-off (length of desk) is 85 meters. The initial velocity of the aircraft is zero, and the final lift-off speed (after going 85 meters) is 77 m/s.

a) How long a time did it take to launch the aircraft?

2.2 sec.

b) What was the average acceleration during the launch?

34.9 m/s² .

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