Projectile motion question?

Question

Which of the following moving objects obey the equations of projectile motion?

a. A jet airplane crosses the sky with its engines thrusting the plane forward

b. A rocket leaves the launch pad

c. A rocket moves through the sky after its engines have failed

d. A stone is thrown under water

Answer 1

C

You can eliminate A and B because anything with engines running isn't a projectile.  D can be eliminated because the water will provide so much resistance to the rock that it won't act much like a projectile.