First Name: ___________________ Last Name: ____________________ Section: _________

September 25, 1996 Physics 201

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 magnitude. You are allowed one 5" x 8" note card and no other references. The exam lasts exactly one hour.

(Do not write below)

SCORE:

Problem 1: __________

Problem 2: __________

Problem 3: __________

Problem 4: __________

TOTAL: ___________

Possibly useful information:

acceleration due to gravity at the earth's surface: g = 9.8 m/s2

First Name: ___________________ Last Name: ____________________ Section: _________

Problem 1

You get into your car at 12:00 noon and drive due east for 5 minutes at an average speed of 60 miles/hr. You then turn left and drive due north for 4 miles, then turn left again and drive due west for 2 miles, arriving at your destination at 12:15 PM. You may use units of miles and miles/hr in your answers below.

a. What total distance did you travel? (5 pts.)

b. What was your average speed for the trip? (5 pts.)

c. What was the magnitude of your displacement vector? (5 pts.)

d. What was the direction of your displacement vector (in degrees) relative to north? (5 pts.)

e. What was the magnitude of your average velocity vector? (5 pts.)

First Name: ___________________ Last Name: ____________________ Section: _________

Problem 2

You toss a 100-g ball vertically upward with an initial speed of 10 m/s.

a. What is the net force on the ball (magnitude and direction) just after it leaves your hand and while it is still moving upward? (5 pts.)

b. At what time after the ball leaves you hand does it reach its maximum height? (5 pts.)

c. What maximum height does the ball reach? (5 pts.)

d. What is the velocity of the ball 2 s after it is tossed? (5 pts.)

e. If you catch the ball as it comes down, bringing it to rest in 0.5 s, what is the magnitude of its average deceleration? (5 pts.)

First Name: ___________________ Last Name: ____________________ Section: _________

Problem 3

You hit a baseball such that it leaves your bat with an initial velocity of 30 m/s at an angle of 30° from the horizontal.

a. At what time after the ball leaves your bat does it pass over the head of a player who is 40 m away from you? (6 pts.)

b. How high is the baseball 1 s after it leaves your bat? (6 pts.)

c. What is the velocity of the baseball when it reaches its maximum height? (6 pts.)

d. How far away from you is the player when he catches your ball at the same height at which it was hit? (7 pts.)

First Name: ___________________ Last Name: ____________________ Section: _________

Problem 4

You pull a 2-kg block across a table at constant velocity by exerting a force of 5 N on a string that makes a 40° angle from the horizontal.

a. Calculate the coefficient of kinetic friction between the block and the surface. (12 pts.)

b. If the force on the string is doubled to 10 N, what is the magnitude of the acceleration of the block? (13 pts.)