AP Physics B – Newton’s Laws Problems
The problems that follow are problems or parts of problems from
Advanced Placement Physics B exams in previous years. In cases where
the word “Mech.” is indicated, the problem is from the Mechanics portion
of the AP Physics C exam. In cases where only part of the original problem
is reproduced here, an indication of which parts are included is described in
parentheses. When you work these problems, all work should be done on
your own paper, with no more than 2 problems per page. Since you will be
stapling in the upper left hand corner of the page, please don’t write there. I
won’t be able to read it. If I can’t read it I won’t grade it. In cases where the
problem directs you to work on the page, ignore the direction and work on
your paper. Problems that are reproduced in their entirety are worth either
10 pts. (and should take about 10 minutes to solve) or 15 pts. (and should
take about 15 minutes to solve).
1.
1976 #1
2.
1979 #2
3.
1980 #1 (parts a and b only)
4.
1981 Mech. #1
5.
1982 #2
A crane is used to hoist a load of mass m1 = 500 kg. The load is
suspended by a cable from a hook of mass m2 = 50 kg, as shown in
the diagram above. The load is lifted upward at a constant
acceleration of 2.00 m/s2.
a. Draw and label the forces acting on the hook and the forces
acting on the load as they accelerate upward.
b. Determine the tension T1 in the lower cable and the tension T2 in
the upper cable as the hook and load are accelerated upward at
2.00 m/s2. Use g = 10 N/kg.
6.
1985 #2 (a, b, c and d from original problem; e and f are Rice
extensions)
a.
b.
c.
d.
Draw a force diagram for the block on the right.
Draw a force diagram for the block on the left.
What is the tension T in the string?
Determine the magnitude of the frictional force acting on the
box on the incline.
The string is then cut.
e. Will the block on the left slide down the incline? Justify your
answer.
f. If the block on the left slides, what is its acceleration?
7.
1986 #1
Three blocks of masses 1.0, 2.0, and 4.0 kilograms are connected by massless
strings, one of which passes over a frictionless pulley of negligible mass, as
shown to the right. Calculate each of the following.
a. The acceleration of the 4.0 kg block
b. The tension in the string supporting the 4.0 kg block
c. The tension in the string connected to the 1.0 kg block
8.
1987 #1
9.
1998 #1
10.
2000 #2
11.
2002 #1
12.
2003 #1
13.
2003 (Form B) #1
14.
2005 #1
15.
2005 (Form B) #1
16.
2007 #1
17.
2007 (Form B) #1 (parts a, b and c only)
18.
2008 #1 (parts a and b only)
(c)
(d) Assume coefficient of friction is smaller than what you calculated to prevent sliding, and the truck
continues to slow down at the rate calculated above until it stops. How far will the crate slide before stopping
if the coefficient of friction is 0.200? Is this friction static or kinetic? Explain.
Answers:
1. b. T = 5000 N
c. M = 625 kg
2
2. a. a = 3 m/s
c. a = 2 m/s2
3. b. T1 = 4 N
c. T2 = 3 N
F
µF
4. a. a = cos! - g sin! " (µg cos! +
sin! )
m
m
# µ cos! + sin! &
1
b. F = mg%
( , F > 0 ) cos! > µ sin!, *tan! <
$ cos! " µ sin! '
µ
5. b. T1 = 6000 N, T2 = 6600 N
6. c. T = 100 N
d. Ff = 13 N
7. a. a = 1.4 m/s2 b. T = 33.6 N
c. T = 11.2 N
M
M g ! µk M1g
MMg
8. b. µ s = 2
c. a = 2
d. T = 1 2 (1+ µk )
M1 + M 2
M1 + M 2
M1
h
c. The block accelerates uniformly d. The block moves at constant velocity e. x = 2h
g
f
f
3f
b. µ =
c. M = (m1 + m2 )sin! "
d. a = gsin ! "
m1gcos!
m1
g
2
b. 30 m/s
c. h = 240 m
d. 8.0 s
b. FN = 98 N
c. T = 603 N
d. No, justify
e. a = 1.63 m/s2
b. d = 975 m
c. 12.5°
bi. -0.75 m/s2
c. 686 N
b. FN = m(g + a) ci. t = 12 s to t = 16 s cii. 500 N
d. t = 7 s to t = 10 s and t = 17 s to t = 20 s
a. t = 8.75 s
c. Ff = 63.4 N
d. µ = 0.27
e. graph on speed vs. time axes
2
b. FN = 177 N
d. a = 0.64 m/s
a. 4.44 m/s2
ci. µ = 0.425 cii. static, explanation d.
9. a. a =
10.
11.
12.
13.
14.
15.
16.
17.
18.
g
2
b. t = 2