the orbit above explains that the ball would keep on going at a constant velocity in a straight path if at any point the pull (gravity) stopped acting on it. pictures provided by N.A.S.A.

the cannon shows F=MA, the force is when it is shot, the masses are the cannon and the bullet and the accelerations are the motion of the cannon and the opposite motion of the bullet. pictures provided by N.A.S.A.

• Force = change of momentum with change of time.
• Force = mass X acceleration.
• Force = mass X change in velocity with time.
• Acceleration is in the way you push or pull an object.
• If you push twice as hard it accelerates twice as much.
• If the mass is doubled then the acceleration is halved.
• Mass is inversely proportional to acc.
• Force is directly proportional to acc.



there is a push in the picture above and both man are affected by it. it's an action with double reaction. pictures provided by N.A.S.A.