PHYS 150 TEST #1 9/14/07 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 your height in meters?
c) Express 200 miles per hour in
meters/second:
89.3 m/s.
2) Add the following vectors. Express your answer in POLAR form:
vector A = (14 meters, 18 degrees)
vector B = (22 meters, 163 degrees)
vector C = (17 meters, 211 degrees)
vector A + vector B + vector C =
(22.4 meters, 174.9 degrees)
Draw a diagram showing each of the vectors A, B, and C and the resultant vector.
3) The sun has a diameter of 865,000 miles and is 93,000,000 miles away. What angle does the sun make with your eye?
a) in degrees: 0.53o; b) in radians: 0.0093 radians; c) in cycles: 0.0015 cycles.
d) A penny has a diameter of 2.0 cm. How far away from your eye should the penny be placed for it to just hide the sun from your eye?
216 cm
e) Draw a diagram showing your eye, the penny, and the sun.
4) Given velocity as a function of time: v(t) = (+33m/s) - (2 m/s4)*t3, and given xo = +17 m,
a-1) Find x(t=0 sec) =
17 m
a-2) Find x(t=3 sec) =
75.5 m
b-1) Find v(t=0 sec) =
33 m/s
b-2) Find v(t=3sec) =
-21 m/s
c-1) Find a(t=0 sec) =
0 m/s2
c-2) Find a(t=3 sec) =
-54 m/s2
5) To the
right is a graph of v(t). On the graphs below it, sketch x(t) and a(t) assuming
that xo< 0.
6) Below are the numerical values of velocity at specific times:
v(0 sec) = + 2.0 m/s
v(1 sec) = + 5.0 m/s
v(2 sec) = + 1.0 m/s
v(3 sec) = - 5.0 m/s
v(4 sec) = - 3.0 m/s
a) Using the numerical method, calculate the average acceleration during the time between t=3 sec and t=4 sec:
+2 m/s2
b) Calculate the position at t=3 sec. You should assume that x = +4 m when t=0 sec [i.e., xo = +4 m]
8.5 m
7) For parts a and b, assume that a car accelerates from rest up to a speed of 30 m/s in a time of 10.0 seconds.
a) What is the average acceleration of the car during the 10 seconds?
3 m/s2.
b) If the acceleration were constant (and equal to the above average) during the 10 seconds, how far did the car go during the 10 seconds?
150 m.
For parts c and d, assume that the average acceleration is the same as that in parts a and b above for the next 10 seconds also.
c) Would the speed after the next 10 seconds (after 20 seconds total) be: less than twice as fast, twice as fast, or more than twice as fast than the speed after only the first 10 seconds?
Twice as fast.
d) How far would the car travel in the second 10 seconds (not including the distance traveled during the first 10 seconds)?
450 m.
8) An object is thrown straight up with an initial speed of 24 m/s from the bottom of a hole 4 meters below ground level and lands on the ground right next to the hole (assume it drifts slightly over to the side so that it does not just fall back down into the hole - but otherwise ignore this side drift ).
a) Draw a picture of this situation.
b) How high will the object go (measured from ground level) before it starts to fall back down?
25.39 m.
e) How long will it take the object to reach its maximum height?
2.45 seconds.