Forces & Motion

Supporting files for this material can be found here.

Force - Any push or pull on an object.

Any force has an agent (the person or thing generating the force) and a receiver (the person or thing that is having the force done to them).  For example, if Mr. Baker throws a ball, then Mr. Baker is the agent because he is putting a force on the ball (the receiver).

Forces have the ability to...
   - make objects move or stop moving,
   - change an object's speed or direction,
   - change an object's shape.

Newton's Laws of Motion
Newton's 1st Law - Inertia
   An object in motion/at rest will stay in motion/at rest until acted
   on by an outside force.
   inertia: a resistance to change in motion.
Newton's 2nd Law

   The change in motion of an object depends on the amount and
   the direction of the force put on that object.
   Force = Mass x Acceleration
   acceleration: change in velocity/speed.
Newton's 3rd Law
   For every action, there is an equal and opposite reaction.

*Note: On Earth, Newton's Laws are influenced by gravity and friction.  For best results, test these Laws in outer space.*

Forces are measured in Newtons (N).  It takes 1N of force to pick up a mass of 100g.

Friction is a force that resists movement.

Forces tend to occur in pairs.  For example, if I am sitting in a chair, gravity is pulling me down while the chair is holding me up.  This shows a downward  force (gravity) and an upward force (the strength of the chair).  If these forces are balanced, then I will stay where I am.  However, if the gravity were to suddenly become stronger than the chair, then the chair would break and I would be pulled down.  On the other hand, if I add to the chair's force by pushing with my legs, my body will rise and I will stand up.

Mass vs. Weight
Mass and weight are not the same thing!  Mass is a measure of how much material is packed into an object.  Weight is a measure of how much pull gravity is exerting on an object.  Mass is measured in grams and kilograms.  Weight is measured in ounces and pounds.


Supporting files for this material can be found here.
Subpages (1): Forces & Motion Files