A machinist turns the power on to a grinding wheel, which is at rest at time t = 0.00 s. The wheel accelerates uniformly for 10 s and reaches the operating angular velocity of 25 rad/s
The wheel is run at that angular velocity for 37 s and then power is shut off. The wheel decelerates uniformly at 1.5 rad/s2 until the wheel stops. In this situation, the time interval of angular deceleration (slowing down) is closest to: A) 17 s
B) 15 s
C) 19 s
D) 21 s
E) 23 s
A
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The experimental data shown tabulated were obtained by passing n-butyl alcohol at a bulk temperature of 15°C over a heated flat plate (0.3-m-long, 0.9-m-wide, surface temperature of 60°C). Correlate the experimental data using appropriate dimensionless numbers and compare the line which best fits the data with Equation 5.38.
GIVEN
n-butyl alcohol flowing over a heated flat plate
Bulk temperature (Tb) = 15°C
Plate surface temperature (Tp) = 60°C
Plate length (L) = 0.3 m
Plate width (w) = 0.9 m
The experimental data given above
FIND
(a) Correlate the data by appropriate dimensionless numbers
(b) Compare line which best fits the data with Equation 5.38
ASSUMPTIONS
Steady state
Alcohol flows parallel to the length of the plate
Plate temperature is uniform
SKETCH
PROPERTIES AND CONSTANTS
From Appendix 2, Table 19: For n-butyl alcohol at the average of the bulk and surface temperatures
(known as the film temperature): 37.5°C.
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