Answer to Question #215764 in Physics for Aru

Question

Determine which of the following moving objects obeys the equations of projectile motion: (A) A ball is thrown in an arbitrary direction. (B) A jet airplane crosses the sky with its engine thrusting the plane forward. (C) A rocket leaves the launch pad. (D) A rocket moves through sky after its engines have failed. (E) A stone is thrown under water

Answer 1

Projectile motion is a form of motion experienced by a launched object. Thus, the only force (except air resistance) acting on the object should be the gravity force.

(A) is correct.

(B) no, since there is an extra force provided by the engine.

(C) no, since there is an extra force provided by the engine.

(D) is correct (engine have failed, so there is no extra force exept the gravity and air resistance)

(E) is correct (water resistance has similar nature to the air resistance).

Ansswer. A, D, E.