Author Question: Where is the sun located relative to a planet's orbit about it? a. at the center of the orbit, ... (Read 362 times)

APUS57 · **on:** Jul 28, 2018

Where is the sun located relative to a planet's orbit about it?
a. at the center of the orbit, which is a circle
b. at the center of the orbit, which is an ellipse
c. at one focus of the ellipse which forms the orbit
d. none of the above

Question 2

What is the half-life of a radioactive element?
a. Half the amount of time it takes the element to decay.
b. The amount of time in which half the quantity of the element will decay.
c. One-half curie of the element.
d. The inverse of the number of decays per second from a sample, expressed in units of time.
e. Half of the amount of the element needed for decay to proceed.