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PHYS1111
SU00 Exam 3
Chs. 8,13, and 14.1-14.5
Dr. Colbert
Show work and units
Multiple choice/short answer
5pts each
Circle the correct multiple choice.
NAME:_________________
1.
a)
2.
A uniform one meter stick balances on a pivot at 0.300m when a mass of 0.200kg is hung
at the 0.100m mark. What is the mass of the stick?
0.667kg
b)
0.200kg
c)
0.150kg
d)
0.500m
=150o
Force=15.0N
AXIS
In the figure above, the force of 15.0N is applied at a distance of 0.600m from the axis.
The force is applied in the direction indicated by the given angle. What is the torque due
to this force?
3.
A spinning object has a rotational kinetic energy of 500.0Joules. The object has a
moment of inertia of 10.0kg m 2. What is the angular speed of the object?
4.
A mass at the end of a spring is pulled to an amplitude of 0.20m and then released.
What fraction of the systems total energy is kinetic when the object passes through the
position at 0.15m?
3/4
b)
1/4
c)
7/16
d)
9/16
a)
5.
A wave has frequency of 1000Hz in a medium with a wave speed of 20m/s. What is the
wavelength?
ALL WORK AND ANSWERS TO THE FOLLOWING PROBLEMS
MUST BE ON THE ADDITIONAL PAPER PROVIDED. NO WORK
ON THIS TEST SHEET WILL BE GRADED (25pts each)
Select 3 problems only
6.
a)
b)
c)
m
d)
e)
In the figure to the left, a hanging mass (m) pulls on a disk with a
Radius R and moment of inertia I starting from rest. This should look
familiar to lab. m, R and acceleration are all measured (knowns). Here
the string is wrapped around the outside of the disk at radius R.
Write out the equations for i) Net force on the mass m, and for ii) net
torque on the disk. (like those discussed in lab).
Solve the two equations (and any others you may need) to write out an
expression for the moment of inertia of the disk. (In terms of m, g, R,
and a).
For m=0.200kg, R=0.100m, and a=1.00m/s2, what is the moment of
Inertia?
What is the tension in the string?
What is the torque on the disk?
7.
A mass of 4.00kg on a spring is pulled a distance of 0.250m from equilibrium and then
released from rest. It takes 0.125s to make a first pass through the equilibrium position.
a)
What is the period and spring constant for this system?
b)
What is the total energy of the system?
c)
What is the kinetic energy of the system as it passes through the equilibrium
position?
d)
Where is the mass 1.5s after it is released?
8.
You are 5.00m from a small speaker (point source of sound) that is emitting 10.0Watts.
The sound is emitted equally in all directions.
a)
What is the intensity of the sound at your location?
b)
How much energy passes through a 1.00cm 2 area (at 5.00m from the source and
properly oriented) in 5.00s?
c)
Where should you stand in order to double the intensity at your location?
9.
You and your lab partner pull a slinky across the hallway floor so that it is stretched out to
10.0meters. Your partner shakes one end through five full cycles in two seconds. The
first wave peak reaches you 0.50s after starting to shake.
a)
What is the wave speed?
b)
What is the frequency and wavelength?
c)
You tied your end of the slinky to a heavier rope under the same tension as the
slinky. The new medium has twice the mass per unit length as the slinky. What
is the new wave speed?
d)
What is the wavelength and frequency in the new medium?