A 750 N box rests on a floor with a coefficient of static friction = 0.800 and coefficient of kinetic friction = 0.600. What is the force of friction if a horizontal force of 550 N is applied to the box?
A. 600 N
B. 450 N
C. 750 N
D. 550 N
E. 440 N
D. 550 N
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Experimental measurements of the temperature distribution during the flow of air at atmospheric pressure over the wing of an airplane indicate that the temperature distribution near the surface can be approximated by a linear equation
where a = a constant = 2 m–1
Ts = surface temperature, K
T? = free stream temperature, K
y = perpendicular distance from surface (mm)
(a) Estimate the convective heat transfer coefficient if
Ts = 50°C and T?= – 50°C.
(b) Calculate the heat flux in W/m2
GIVEN
Air flow over an airplane wing
Temperature distribution is given by the expression above
Surface temperature (Ts) = 50°C
Ambient temperature (T?) = – 50°C
FIND
(a) The convective heat transfer coefficient
ch
(b) The heat flux (q/A) in W/m2
ASSUMPTIONS
Steady state conditions
Uniform surface temperature
SKETCH
PROPERTIES AND CONSTANTS
From Appendix 2, Table 28, for air at 0°C, the thermal conductivity (k) = 0.0237 W/(m K)
Venus is often called Earth's sister planet because it is similar to the Earth in terms of
a. mass. b. size. c. density. d. mass, size, and density.
According to this graph, the minimum size of an object that could cause a mass extinction is a little less than _____.
A. 10 m B. 100 m C. 1 km D. 10 km E. 100 km
An object is being acted upon by three forces and moves with a constant velocity. One force is 60.0 N along the x-axis, the second is 75.0 N along the y-axis. What is the magnitude of the third force?
A) 135 N B) 15.0 N C) 48.0 N D) 67.5 N E) 96.0 N