1. FORCES AND NEWTON’S LAWS OF MOTION
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2. 1 pound = 4.45 Newtons
500 lb Elephant = 2,225 N

3. Newton’s 1st Law
An object at rest remains at rest, and an object in motion remains moving at that velocity, unless a net external force causes the motion to change.
We often refer to Newton’s first law as the law of inertia.

4. Inertia
The tendency of an object to stay in motion , or resist change in motion
mass is a measure of inertia

5. BMW Inertia
Physics Force - U of Minnesota

6. Newton’s second law

9. A student pushes a loaded sled whose mass is 240 kg for a distance of 2.3 m over the frictionless surface of a frozen lake. He exerts a horizontal force equal to 130 N. If the sled starts from rest, what is its final velocity ?

10. Equilibrium
Equilibrium – a condition when the forces on an object are balanced.
Static Equilibrium = an object at rest
Dynamic Equilibrium = an object travels with constant velocity

11. Unbalanced Forces
Unbalanced forces accelerate an object

12. F = ma becomes Fg= mg g = acceleration due to gravity g = 9.8 m/s2
The Weight (Fg) of an object is defined as the amount of gravitational force acting on its mass.
F = ma becomes Fg= mg
g = acceleration due to gravity
g = 9.8 m/s2

13. Normal Force (FN) Tension (FT)
A force exerted between 2 objects being squeezed together in a direction normal (or perpendicular), to surfaces in contact.
Tension (FT)
Force exerted through string, rope, cord, chain, etc.

18. An elevator cable supports an empty elevator car of mass 300 kg
An elevator cable supports an empty elevator car of mass 300 kg. Determine the tension in the cable when the elevator car is (a) at rest and (b) the car has a downward acceleration of 2.0 m/s2.
A) FT = W = mg = (300 kg)(10 m/s2) = 3000 N. B) W FT