True-false questions are worth 2 points each, three-choice multiple
choice questions are worth 3 points each, five-choice multiple choice
questions are worth 6 points each. The maximum possible score is 113.
The mean score was 76.4; the median was 77.
The exam period was 90 minutes. Click here to see page1
page2 of the formula sheet that came
with the exam.
Unless told otherwise, you should assume that the acceleration of
gravity near the surface of the earth is 9.8 m/s2 downward
and ignore any effects due to air resistance.
A block of 10 kg rests on the (horizontal) floor. The coefficient of
kinetic friction between the block and the floor is 0.1. You push
horizontally on the block with a force F = 30 N.
What is the work done on the block by the force F after the block has
moved a distance d = 2 m (in the same direction of the force on the
(a) 20 J
(b) 30 J
(c) 40 J
(d) 50 J
(e) 60 J
(c) the same
(a) v = 0
(b) v = mgh
(c) v2 = 2gh
Two 80 kg skiers, A and B, race on a pair of trails down a mountain.
Both trails drop a vertical distance of 100 m. Skier A chooses a trail
that zigzags back and forth and has a total length of 1000 m. Skier B
chooses a trail that heads straight down the steepest part of the
mountain and has a total length of 250 m. Ignoring friction and air
resistance, which skier is moving faster at the bottom of the
(c) A and B have the same speed.
(c) A and B get to the bottom at the same time.
(a) 175 W
(b) 196 W
(c) 229 W
(d) 344 W
(e) not enough information given
A 1.0 kg hammer moving at 3 m/s strikes an initially stationary 10 kg
metal block head-on and bounces straight back at a speed of 0.5 m/s.
What is the speed of the block after the collision?
(a) 0.11 m/s
(b) 0.27 m/s
(c) 0.35 m/s
(d) 0.54 m/s
(e) 0.99 m/s
(c) completely inelastic.
(a) 50 N
(b) 100 N
(c) 200 N
(d) 300 N
(e) 800 N
(a) 0 m/s
(b) 1 m/s
(c) 2 m/s
(d) 3 m/s
(e) 5 m/s
(a) 0 m/s
(b) 25 m/s
(c) 50 m/s
(d) 100 m/s
(e) 150 m/s
(a) mechanical energy was not conserved
(b) total energy was not conserved
(c) both (a) and (b)
There are two identical looking disks A and B. A and B have the
same mass MA = MB, but the moment of
inertia IA of A around its symmetry axis is larger
than that IB of B. A and B are released gently from
the same height on the incline as illustrated below.
Suppose the slope is frictionless. Which disk reaches the bottom of
the incline first? (Note: MA = MB and
IA > IB)
(c) A and B arrive simultaneously.
There is a very light stick of length 3 m. At its one end is an
almost point like mass of 5 kg, and at the other end of the stick is
another almost point like mass of 9 kg. The stick with two masses is
hung from the ceiling with two strings so that it is horizontal as
illustrated below. (The dotted line segment in the figure is for the
second question below.)
Find the tension T in the right string.
(a) 0 N
(b) 49 N
(c) 69 N
(d) 88 N
(e) 127 N
(a) T increases.
(b) T does not change.
(c) T decreases.
(a) F = Lt / (2R)
(b) F = L / (2Rt)
(c) F = L / (2t)
(d) F = L / (Rt)
(e) F = Lt / R
At one end of a massless wire with the partially circular shape shown
in the figure is a mass M = 2 kg. The other end is on a fulcrum
O, and this balancing toy is stationary. That is, the mass is sitting
vertically below the fulcrum O. What is the net torque around the corner
A? The angle θ is π/6 and R = 0.5 m.
(b) -RMg / 2
(d) RMg / 2
(b) 0.5 kg·m2
(c) 1.0 kg·m2
(d) 1.5 kg·m2
(e) 2.5 kg·m2
(c) stays the same.
If the floor and the slope are perfectly frictionless, the disk
slides without rolling. The largest vertical displacement of the center
of mass of the disk is h as shown in the figure.
If instead the floor and the incline have friction, the disk
rolls without slipping. What is the largest vertical displacement of
the center of mass, if the translational speed of the disk on the floor
is the same as before?
(a) 0.5 h
(b) 0.67 h
(c) 0.75 h
(e) 1.5 h
(a) 33 N
(b) 67 N
(c) 98 N
(d) 131 N
(e) 164 N