NEWTON´S LAWS OF MOTION

1^st Law (Law of Inertia) – “An object at rest will stay at rest, and an object in motion will stay in motion at constant velocity, unless acted upon by an unbalanced force” “An object at rest will stay at rest, and an object in motion will stay in motion at constant velocity, unless acted upon by an unbalanced force”

“Inertia is the tendency of an object to resist changes in its velocity: whether in motion or motionless”

Example: “Once airborne, unless acted on by an unbalanced force (gravity and air – fluid friction), it would never stop! Unless acted upon by an unbalanced force, this golf ball would sit on the tee forever”.

2^nd Law – Force equals mass times acceleration: “The net force of an object is equal to the product of its mass and acceleration, or F=ma”    “When mass is in kilograms and acceleration is in m/s/s, the unit of force is in newtons (N)”

 “One newton is equal to the force required to accelerate one kilogram of mass at one meter/second/second”

Example: How much force is needed to accelerate a 1400 kilogram car 2 meters per second/per second?

1. Write the formula

2. F = m x a

3. Fill in given numbers and units

4. F = 1400 kg x 2 meters per second/second

5. Solve for the unknown

6. 2800 kg-meters/second/second = 2800 N.

3^rd Law – For every action there is an equal and opposite reaction. “According to Newton, whenever objects A and B interact with each other, they exert forces upon each other. When you sit in your chair, your body exerts a downward force on the chair and the chair exerts an upward force on your body”

There are two forces resulting from this interaction - a force on the chair and a force on your body. These two forces are called action and reaction forces.

Example: “Consider the propulsion of a fish through the water. A fish uses its fins to push water backwards.  In turn, the water reacts by pushing the fish forwards, propelling the fish through the water”