Select all the correct answers. Which situations describe an elastic collision?
A. Two glass marbles bounce off each other.
B. Rodrick flops onto his sofa and sinks into the cushion.
C. A tossed water balloon flattens when it lands on the grass.
D. A bowling ball knocks over five pins.

If a clock aboard a space ship traveling at 0.900 c of the speed of light relative to earth chimes once at the beginning of the hour and again when it reads one hour later, how much time would an observer on earth say elapsed between the two chimes?

Often called simply "velocity," this is the velocity of an object at a particular moment in time.

Beryl states that insulation with the smallest possible thermal conductivity is best to keep a house warm in winter, but worst for keeping a house cool in summer. sapphire insists the reverse is true: low thermal conductivity is good in the summer, but bad in the winter. which one, if either is correct? a. beryl, because low thermal conductivity results in low heat transfer. b. beryl, because low thermal conductivity results in high heat transfer. d. sapphire, because low thermal conductivity results in high heat transfer. e. neither, because low heat transfer is desirable both in summer and in winter.