John throws a rock down with speed 20 m/s from the top of a 30-m tower. If g = 9.8 m/s2 and air resistance is negligible, what is the rock's speed just as it hits the ground?
a. 12 m/s
c. 31 m/s
b. 28 m/s
d. 78 m/s
C
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A light ray in air strikes a glass plate whose index of refraction is 1.42. Some of the light reflects off the surface of the plate, but most of it enters the glass
If the angle of refraction is one-half the angle of reflection, the angle of refraction is closest to which one of the following angles? A) 45° B) 43° C) 41° D) 39° E) 37°
As you walk away from a plane mirror on a wall, your image
A) gets smaller. B) may or may not get smaller, depending on where the observer is positioned. C) is always a real image, no matter how far you are from the mirror. D) changes from being a virtual image to a real image as you pass the focal point. E) is always the same size.
Going from medium mass nuclei to heavy nuclei, the average binding energy per nucleon
A) does not change. B) decreases. C) behaves randomly with no clear pattern. D) doubles. E) increases.
Would we call a large earthquake or major volcanic eruption a natural disaster if no humans were killed or buildings destroyed?
What will be an ideal response?