A space probe travels directly outward from Earth. At t=0 it is at x=0m. At t=20s it is at x=400m. At t=50s its velocity is measured to be 28m/s outward. Assuming the probe’s acceleration is constant, what is its position at t=80s?
a) 2.2×103m
b) 2.1×103m
c) 2.9×103m
d) 1.8×103m