A projector lens is needed to form an image on a screen 20 times the size of its corresponding object. The screen is located 8.0 m from the lens. What is the required focal length of the lens?
a. 0.32 m
c. 0.73 m
b. 0.38 m
d. 1.25 m
B
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A fermion has integral spin
Indicate whether the statement is true or false
A 3.00-m-long ladder, weighing 200 N, leans against a smooth vertical wall with its base on a horizontal rough floor, a distance of 1.00 m away from the wall. The ladder is not completely uniform, so its center of gravity is 1.20 m from its base
What force of friction must the floor exert on the base of the ladder to prevent the ladder from sliding down? A) 93.3 N B) 130 N C) 28.3 N D) 102 N E) 150 N
Uranium serves as the source of the Sun's energy because
a. uranium atoms can be fissioned into lighter atoms and energy. b. uranium atoms can be fused into helium and energy. c. uranium atoms can be fused into hydrogen and energy. d. none of the above because fusion of hydrogen atoms serves as the Sun's source of energy. e. none of the above because fusion of helium atoms serves as the Sun's source of energy.
A diver shines light upward to the surface of a smooth pond at 20° to the normal. Most light passes into the air above while the part that reflects back into the water makes an angle to the normal of
A) less than 20°. B) 20°. C) more than 20°. D) all refracts, none reflects.