Question

The Voyager 1 spacecraft, shown below, completed its space exploration mission in 1980 and has since been traveling away from Earth at a speed of about 39,000 miles per hour.


Image courtesy of NASA

If no unbalanced forces act on Voyager 1, then
A.
its speed will slowly decrease.
B.
its speed will slowly increase.
C.
the direction of its motion will reverse.
D.
it will continue traveling at the same speed.

Answer 1

D. If no unbalanced forces act, the net force is zero, so acceleration is zero and Voyager 1 will continue moving with the same velocity (same speed and direction).