Consider a rock interacting gravitationally with the earth, and choose the interaction’s potential energy to be zero if the rock is at the ground level. A person standing at the bottom of a well throws the rock vertically upward from 20 m below ground level. The rock makes it all the way up to 1 m below ground level before falling back into the well. The total energy of the rock–earth system is
A. negative.
B. zero.
C. positive (in this particular case).
D. positive (because energy is always positive).
E. The answer depends on information not specified.
A. negative.
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Consider a two-slit interference experiment like the one shown in figure Q3.7b. The distance between adjacent bright spots in the interference pattern on the screen (A) increases, (B) decreases, or (C) remains the same if, (a) The wavelength of the light increases.
A. increases B. decreases C. remains the same
The element barium should produce compounds most similar to those of
a. sodium. b. nitrogen. c. carbon. d. calcium.
What is the approximate wavelength of red light?
A. 7 cm B. 5 m C. 400 nm D. 700 nm
A cup of coffee is enclosed on all sides in an insulated container 1/2 cm thick in the shape of a cube 10 cm on a side. The temperature of the coffee is 95°C, and the temperature of the surroundings is 21°C. Find the rate of heat loss (in J/s) due to conduction if the thermal conductivity of the cup is 2 × 10^?4 cal/s/cm/°C
a. 62 b. 74 c. 230 d. 160 e. 12