For a mass moving up and down on a spring, what causes simple harmonic motion?
a. weight
b. gravity
c. restoring force
d. spring constant

How does the image distance (di) of a convex lens compare with the image distance of a concave lens? a. the image distance of the convex lens is positive, and that of the concave lens is negative. b. both are negative for a virtual image. c. both are positive for a virtual image d. the image distance of the convex lens is negative, and that of the concave lens is positive.

How can one distinguish breccia from conglomerate? a. breccia contains angular clasts and conglomerate contains rounded clasts. b. breccia contains rounded clasts and conglomerate contains angular clasts. c. different minerals cement breccia than cement conglomerate. d. breccia contains sand and conglomerate contains silt.

Which of the following explains why it took so long for the public to accept the negative health effects of smoking? a)people were waiting for counter reasons, and those were presented. b)scientists had not completely finalized their results, which took 30 years. c)cigarettes were cheaply available and media channels were very inefficient. d)cigarette manufacturers were trying hard to bring an alternative into the market