Physics 113 –Summer 2008
To be stapled on top of #4,#3,#2,#1 and turned
in with Exam#3 to receive extra credit
Student’s name ________________________ Total previous points
accumulated:
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12.1- Static
equilibrium. Give
the horizontal force applied at the highest point to keep a wheel of mass M
from rolling down a slope inclined at angle θ to the horizontal.
13.1- SHM. Before take-off your keys
connected to a thread make 90 cycles per minute, while the plane is
accelerating they make 91 cycles per minute. What is the plane acceleration?
13.2- SHM. Two blocks, one on top of
the other are undergoing SHM of angular frequency 10 rad/s
since the lower one is laying on a frictionless surface and connected to a
14.1- Wave
properties. Given
y=2 cos(π(x-t/2))
where x,y are in cm, and t in seconds. Provide (a)
amplitude (b) wavelength (c) period (d) speed (e) direction of propagation of
the wave.
14.2- Wave
on a string. Mass
m1 is vertically attached to a wire of linear density 1.5 g/m, the
other end of the wire runs through a pulley and is horizontally tied to a wall.
The speed of the transverse wave in the horizontal section of the wire is
30m/s. If a mass m2 is added to m1 this speed becomes
40m/s. Find m2.
14.3- Interference. You are in an aircraft
with two engines running at 500rpm and 506 rpm. How often do you hear the sound
intensity increase as a result of wave interference?
14.4- Standing
waves. A
1m long string is clamped at both ends (a) what is the longest wavelength? (b) if the speed is 50m/s, what is the lowest standing-wave
frequency?
14.5- Doppler
effect. A
fire truck’s siren wails at rest at 1200Hz. However you hear it at 1500Hz when
the truck is approaching, how fast is the truck going?
15.1- Bouyancy. How
much helium (density 0.18 kg/m3) is needed to lift a balloon
carrying two people in a basket, with the total mass except air is 280kg.
Repeat for hot air, with density 10% less than that of surrounding atmosphere