PHYS 201 TEST #1             9/14/16           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) c) Express 10 meters/second in miles per hour: (8.0 m/s is a runner who can do the 100 m dash in 10 seconds)

22.4 mph.

 

2)  What angle does a dime make when viewed from 40 cm away from the eye (about an arm’s length) given that the diameter of the dime is 1.8 cm?

a) in degrees: 2.58o;

b) in radians 0.045 radians;

c) in revolutions: 0.00716 revs                 

d) Is this angle [smaller than, the same as, or larger than] the angle than the moon makes when viewed from the earth (which is 0.5o)

 

Larger than.

 

3) a) Convert the following vector (-28 cm, 18 cm) from rectangular to polar form:

(33.3 cm, 147.3o)

 b) Convert the following vector: (42 m, 1234°) from polar to rectangular form:

(-29.2 m, 30.2 m)

 

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

            A = ( 7 m, 50°)

            B = (12 m, 130°)

            C = ( 6 m, 210°)

(14.3 m, 126.0o)

 

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

 

 5) A runner runs a 1 mile race in 6 minutes even.

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

a) in miles/hour:

10 mph.

b) in m/s:

4.46 m/s.

c) At this average speed, how long would it take the runner to run 100 meters?

 22.4 seconds

d)  At this average speed, how long would it take the runner to run a marathon (26 miles)?

156 minutes = 2 hours and 36 minutes = 9,360 seconds.

 

v vs t graph6) To the right is a graph of v(t). On the graphs below it, sketch x(t) and a(t) assuming that xo< 0.

 

 

 

 

 

x vs t graph 

 

 

 

 

 

a vs t graph 

 

 

 

 

 

 

7) Given the following velocity data:

v(0 sec.) =   -3 m/s

v(1 sec.) =    0 m/s

v(2 sec.) =   +4 m/s

v(3 sec.) =   +9 m/s

and given that xo =  -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?

+4.0 meters.

 

8) An object is thrown upwards with an initial velocity of 34 m/s from the top of a building that is 9 meters high.

 

 a) How high (measured from the ground) does the object reach at its highest point (ignoring air resistance and assuming constant acceleration due to gravity)?

 

67.98 m.

 

 b) How long will it take the object to reach that height?

 

3.47 seconds

 

 c)  How long will it take the object to finally reach the ground (as measured from when the object was initially thrown)?

 

6.66 s.

 

 

Return to PHYS 201 page