Question

if it were possible to remove gravity and friction, think about what would happen to a football if it were tossed into the air. assume the football is in a vacuum (no gravity or friction) and is continuously moving, which force(s) would be acting on the ball?
a force must be applied to it when it slows to a position of rest.
a force must be applied to it before it slows to a position of rest.
no force is needed; an object in motion stays in motion.
many forces must act upon it to keep it in motion.

Explanation:

Newton's First Law of Motion (Law of Inertia) states that an object in motion will stay in motion with a constant velocity (same speed and direction) unless acted upon by a net external force. In a vacuum with no gravity or friction, there are no net external forces. So, a moving football will continue moving without the need for a force to keep it in motion.

• Option 1: A force is not needed when it slows (since there's no friction/gravity to cause slowing, and force is for changing motion, not for slowing here in this ideal case).
• Option 2: A force is not needed before it slows (as there's no cause for slowing without external forces).
• Option 3: Correct. According to Newton's First Law, in the absence of net external forces, an object in motion remains in motion. So no force is needed for the football to stay in motion.
• Option 4: Many forces are not needed. In the ideal vacuum with no friction/gravity, there are no forces acting, and the object stays in motion.

Answer:

C. No force is needed, an object in motion stays in motion. (Note: Assuming the options are labeled as A, B, C, D with the third option being "No force is needed, an object in motion stays in motion")