The interstellar reddening does not shift the _______________ of spectral lines, as does the Doppler effect
Fill in the blank(s) with correct word
wavelength
You might also like to view...
A 3.50-kg block is pulled along a moving conveyor belt at a constant speed of 0.500 m/s relative to a stationary observer while the belt moves at a constant speed of 0.200 m/s in the same direction. If the coefficient of kinetic friction is 0.400, the magnitude of the mechanical energy dissipated, in J, caused by the force of friction on the block in 8.00 s is
A. 5.6. B. 22.0. C. 32.9. D. 54.8. E. 76.8.
Surface hardening of metallic machine components, such as ball and roller bearings, is carried out in a heat treatment process where the surface temperature is increased to a desirable level without altering the internal temperature substantially. In one such operation, steel ball (spherical) bearings with a diameter of 25 mm, initially at 25°C, are immersed in a very high temperature (1000°C) molten electrolyte-solution bath and quickly removed when the temperature at a depth of 1 mm from the outer surface of the steel ball attains 725°C. If the convective heat transfer coefficient between the steel ball and the bath liquid is assumed to be 4.95 kW/(m2 K), determine the time required for attaining the surface hardening condition.
GIVEN
Steel ball bearing diameter (d)= 25 mm=0.025 m
Initial temperature (To) = 25°C
Temperature of electrolyte solution (T?) = 1000°C
The heat transfer coefficient (hc) = 4.95 kW/(m2 K) = 4950 W/(m2 K)
Radius of the surface where temperature of 7250C is attained= 11.5 mm
FIND
Time required for attaining temperature of 7250C at depth of 1 mm from outer surface.
ASSUMPTIONS
constant bath temperature, thermal properties and heat transfer coefficient
SKETCH
Younger stars have more heavy elements because
a. old stars destroy heavy elements as they age. b. young stars burn their nuclear fuels faster. c. the heavy elements were made in previous generations of stars. d. heavy elements haven't had time to settle to the core of these younger stars. e. all of these
A car travels for 140 km at 70.0 km/hr. It then travels an additional distance of 60.0 km 40.0 km/hr. The average speed is
A. 61.0 km/hr. B. 57.1 km/hr. C. 53.3 km/hr. D. 46.7 km/hr. E. 45.0 km/hr.