PHYS 2001 : Make Up Exam 2
Exam 2 MAKE UP KEY
PHYS 2001- FALL 2015
Dr. Mesa
1. While you sleep, your body is using energy at a rate of 77 W. How many food calories are used during an eight
hour period of sleep? One food calorie (1C) = 4186 joules.
A. 66 C
B. 240 C
C. 530 C
D. 710 C
E. 1200 C
2. A roller coaster starts at the top of a hill, height y0, with some initial velocity v0. The speed at yb is: (HINT: Use
conservation of mechanical energy)
A.
vb=2g(y0−yb)+v0
2
B.
vb=2v0
2
C.
vb=v0
2
D.
vb=g(y0−yb)+v0
2
E.
vb=2g(y0−yb)
+ (3 p.c)
3. Two masses m1 and m2 collide elastically. Which of the following is true of the total linear momentum p and
total kinetic energy (KE). ?
A. p is conserved but KE increases
B. KE is conserved but not p
C. both p and KE are conserved
D. neither p nor KE is conserved
E. p is conserved but KE decreases
4. The diagram shows a circular piece cut out of a larger circular metal plate. State where the center of mass of the
final object lies.
A. at A
B. at B
C. between A and B
D. between B and C
E. at C
KEo+PEo=KEf+PEf
1
2mv0
2+mgy0=1
2mvf
2+mgyb
vb=2g(y0−yb)+v0
2
y0
yb
vb
yf
v0
R
2R
A
B
C
5. A wheel that is rotating at 33.3 rad/s is given an angular acceleration of 2.15 rad/s2. Through what angle has the
wheel turned when its angular speed reaches 72.0 rad/s?
A. 83.2 rad
B. 316 rad
C. 697 rad
D. 66.8 rad
E. 948 rad
6. A stationary 5 kg rod AC is held against a wall by a rope and friction between the rod and the wall. The uniform
rod is 1 m long and θ = 30°. The magnitude of the tension on the rod form the rope is:
A. 10 N
B. 35 N
C. 25 N
D. 10 N
E. 49 N
7. Two cylinders of the same size and mass roll down an incline. Cylinder A has most of its weight concentrated at
the rim, while cylinder B has most of its weight concentrated at the center. Which reaches the bottom of the incline
first?
A. A
B. B
C. Tie
D. Neither
E. Not enough information given to determine
8. A child stands on the edge of a merry-go-round, which spins without friction. The child slowly walks towards
the center of the platform. As the child moves toward the center, the magnitude of the platform's angular velocity
(𝜔):
A. Increases
B. Decreases
C. Remains constant
D. Equals to zero
E. Not enough information given to determine
ω
2=
ω
0
2+2
αθ
ω
2−
ω
0
2
2
α
=
θ
