The turntable of a record player has an angular velocity of 8.0 rad/s when it is turned off. The turntable comes to rest 2.5 s after being turned off. Through how many radians does the turntable rotate after being turned off? Assume constant angular acceleration
a. 12 rad
b. 8.0 rad
c. 10 rad
d. 16 rad
e. 6.8 rad
c
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The temperature of n moles of a gas is increased from Ti to Tf at constant volume. If the molar specific heat at constant volume is CV and is independent of temperature, then change in the entropy of the gas is:
A. nCV ln(Tf /Ti) B. nCV ln(Ti/Tf ) C. nCV ln(Tf ? Ti) D. nCV ln(1 ? Ti/Tf ) E. nCV (Tf ? Ti)
Parallel-Plate Capacitor: A 3.0-pFcapacitor consists of two large closely-spaced parallel plates that have surface charge densities of ±1.0 nC/mm2. If the potential across the plates is 23.0 kV with only air between them, find the surface area of each of the plates. (?0 = 8.85 × 10-12 C2/N ? m2)
A. 69 mm2 B. 0.014 mm2 C. 35 mm2 D. 0.0072 mm2
The above image is an example of a ________
a. protostellar disk
b. YSO
c. protostar
d. Herbig-Haro object
The intake manifold of an automobile engine can be approximated as a 4-cm-ID tube, 30 cm in length. Air at a bulk temperature of 20°C enters the manifold at a flow rate of 0.01 kg/s. The manifold is a heavy aluminum casting and is at a uniform temperature of 40°C. Determine the temperature of the air at the end of the manifold.
GIVEN
• Air flow through a tube
• Tube inside diameter (D) = 4 cm = 0.04 m
• Tube length (L) = 30 cm = 0.30 m
• Inlet bulk temperature (Tb,in) = 20°C
• Air flow rate (m ) = 0.01 kg/s
• Tube surface temperature (Ts) = 40°C
FIND
• Outlet bulk temperature (Tb,out)
ASSUMPTIONS
• Steady state
• Constant and uniform tube surface temperature
SKETCH
PROPERTIES AND CONSTANTS
for dry air at the inlet bulk temperature of 20°C
Thermal conductivity (k) = 0.0251 W/(m K)
Absolute viscosity (?) = 18,240 × 10–6 (Ns)/m2
Prandtl number (Pr) = 0.71
Specific heat (c) = 1012 J/(kg K)