September 25, 1998 Physics 207
Exam 1
Print your name and section clearly on all five pages. (If you do not
know your section number, write your TA’s name.) Show all work in the space
immediately below each problem. Your final answer must be placed in the
box provided. Problems will be graded on reasoning and intermediate steps
as well as on the final answer. Be sure to include units wherever necessary,
and the direction of vectors. Each problem is worth 25 points. In doing
the problems, try to be neat. Check your answers to see that they have
the correct dimensions (units) and are the right order of magnitudes. You
are allowed one 8½ x 11" sheet of notes and no other references.
The exam lasts exactly 50 minutes.
(Do not write below)
SCORE:
Problem 1: __________
Problem 2: __________
Problem 3: __________
Problem 4: __________
TOTAL: ___________
First Name: ___________________ Last Name: ____________________ Section: _________
1. While driving down a highway, you clock the time between two successive mile markers at 70 seconds.
a. What is your average speed in mi/hr? (5 pts.)
b. Assuming the markers are accurate, but your time estimate has an
error of + 1 s, what is the error in your speed estimate in mi/hr?
(5 pts.)
c. If 1 km = 0.621 mi, what is your average speed in m/s? (5 pts.)
d. If you filled the gas tank 5 hours ago and it is now ¼ full,
how many more miles can you go before running out of gas, assuming your
speed has been and will remain the same as calculated in part a above?
(5 pts.)
e. If your gas tank holds 18 gallons, how many miles per gallon are
you getting? (5 pts.)
First Name: ___________________ Last Name: ____________________ Section: _________
2. A ball is thrown vertically upward and reaches a height of 12 m before falling back to the point at which it was released.
a. With what initial speed was the ball released? (9 pts.)
b. How much time elapsed from the instant the ball was released until
it reached its maximum height? (8 pts.)
c. If the ball was released 2 m above the ground, at what speed does
it hit the ground? (8 pts.)
First Name: ___________________ Last Name: ____________________ Section: _________
e. What was the average velocity? (5 pts.)
First Name: ___________________ Last Name: ____________________ Section: _________
4. A field goal in American football requires kicking the ball from ground level over a goal post 3 meters high. Assume a kicker kicks the ball at an angle of 45° above the ground at a horizontal distance of 35 yards (32 meters) from the goal post.
a. What initial speed must the ball have to just clear the goal post?
(5 pts.)
b. How long is the ball in the air before crossing the goal post? (5
pts.)
c. How far beyond the goal post does the ball hit the ground? (5
pts.)
d. At what speed does the ball strike the ground? (5 pts.)
e. At what angle from the horizontal does the ball strike the ground?
(5 pts.)