After three half-lives have elapsed, the amount of an 8.0 g sample of a radionuclide that (hint: pizza slices)
a. Remains undecayed is 1.0 g
b. Has decayed is 7.09
c. Remains undecayed is one-third the original amount
d. More than one correct response
e. No correct responsel

•• al and bert are jogging side-by-side on a trail in the woods at a speed of 0.75 m/s. suddenly al sees the end of the trail 35 m ahead and decides to speed up to reach it. he accelerates at a constant rate of 0.50 m/s2, while bert continues on at a constant speed. (a) how long does it take al to reach the end of the trail? (b) once he reaches the end of the trail, he immediately turns around and heads back along the trail with a constant speed of 0.85 m/s. how long does it take him to meet up with bert? (c) how far are they from the end of the trail when they meet?

What is the earliest point in the universe that we can observe? why can’t we see back further than this?

It is really hard for me right know