Which statement accurately describes the ultraviolet catastrophe? O A. A hot lightbulb gave off white visible light instead of ultraviolet

light.

B. An excited gas gave off ultraviolet light rather than an emission

spectrum

O C. A hot lightbulb gave off ultraviolet light instead of white visible

light

D. An excited gas gave off an emission spectrum rather than

ultraviolet light

Apulley system lifts a 500-ib block 1.0 foot with an effort of only 50 ib. if the 50 ib moves 30 feet, calculate the efficiency of the pulley system. a. 30% b. 33% c. 70% d. 67%

Alice added sodium chloride to water and stirred the water for several minutes. alice is most likely trying to demonstrate that ionic compounds a. are hard. b. can dissolve. c. are clear. d. can melt.

In a wind tunnel the speed changes as the cross sectional area of the tunnel changes. if the speed in a 6' x 6' square test section is 100 mph, what was the speed upstream of the test section where the tunnel measured 20' x 20'? use conservation of mass and assume incompressible flow. conservation of mass requires that as the flow moves through a path or a duct the product of the density, velocity and cross sectional area must remain constant; i. e., that ova-constant. a model is being tested in a wind tunnel at a speed of 100 mph if the flow in the test section is at sea level standard conditions, what is the pressure at the model's stagnation point? (a) the tunnel speed is being measured by a pitot-static tube connected to a u- tube manometer. what is the reading on that manometer in inches of water? (b) at one point on the model a pressure of 2058 psf is measured. what is the local airspeed at that point?