Forces+and+Newton's+Laws

Forces and Newton's Law's __1st Law__ ** I. Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it. ** -Inertia - An object's tendancy to resist changes in a state of motion

Ex.1 (moving) - Baseball bat hitting the baseball to make it go in the opposite direction
==Ex.2 (stationary) - At the starting line of a nascar race, when the car starts moving, it is gaining speed so quickly that your body sinks back into the seat. This is because your body wants to remain where it was originally sitting, rather than follow along with the moving car.==

__2nd Law__ ** II. The relationship between an object's mass //m//, its acceleration a, and the applied force //F// is //F = ma//. Acceleration and force are vectors and in this law the direction of the force vector is the same as the direction of the acceleration vector **

-Net Force is also known as a resultant force. It is a vector that is produced when two or more forces act upon one object. The vectors are added together to calculate the force that is acting upon the object. -



1) Mass is a measurement of the amount of matter something contains, while Weight is the measurement of the pull of gravity on an object. 2) Mass is measured by using a balance comparing a known amount of matter to an unknown amount of matter. Weight is measured on a scale. 3) The Mass of an object doesn't change when an object's location changes. Weight, on the otherhand does change with location.

**The moon is much smaller than the earth. As a result, the force of gravity on the moon is only about one sixth as strong as gravity on earth. Gravity is what holds us down on the earth's (or moon's) surface.

If you were to weigh yourself on a scale here on earth and then could take that same scale to the moon and weigh yourself there, the weight read on the moon would be 1/6 your earth weight. So, If you weighed 100 pounds on earth, you would weigh only about 16 pounds on the moon.**

Force Diagram

slipping: = // m k* //F(N) || Direction opposing relative motion. ||
 * **Force ** || **Symbol ** || **Magnitude ** || **Direction ** ||
 * Gravity (weight) || F(G) || <span style="font-family: Arial,Helvetica;">= mobject*g (9.8 m/s2) || <span style="font-family: Arial,Helvetica;">Downward ||
 * <span style="font-family: Arial,Helvetica;">Normal (surface) || <span style="font-family: Arial,Helvetica;">F(N) || <span style="font-family: Arial,Helvetica;">any (up to breaking load) || <span style="font-family: Arial,Helvetica;">perpendicular to surface ||
 * <span style="font-family: Arial,Helvetica;">Tension || <span style="font-family: Arial,Helvetica;">F(T) || <span style="font-family: Arial,Helvetica;">any (up to breaking load) || <span style="font-family: Arial,Helvetica;">along string/rope/chain ||
 * <span style="font-family: Arial,Helvetica;">Friction || <span style="font-family: Arial,Helvetica;">F(fr) || <span style="font-family: Arial,Helvetica;">not slipping: between zero and // m <span style="font-family: Arial,Helvetica;">s* //<span style="font-family: Arial,Helvetica;">F(N)

<span style="font-size: 120%; color: #de99fa; font-family: Impact, Charcoal, sans-serif;">__ 3rd Law __ <span style="font-size: 120%; color: #9700ff; font-family: Impact, Charcoal, sans-serif;">- in every interaction, there is a pair of forces acting on the two interacting objects. The size of the forces on the first object __equals__ the size of the force on the second object. The direction of the force on the first object is __opposite__ to the direction of the force on the second object. Forces __always__ come in pairs - equal and opposite action-reaction force pairs.

If a surface and a line are at right angles to each other, we say the line is **normal**. So any line that is at a right angle to the surface is called a normal line. If there is a force coming from the surface and at a right angle to the surface then we call it a **Normal** line. Any force coming from the surface and acting at a right angle to the surface is called the **Normal Force**.

<span style="font-size: 110%; font-family: Georgia, serif;"> **__ FRICTION __** <span style="font-size: 110%; font-family: Georgia, serif;">**Friction** is the force <span style="font-size: 110%; font-family: Georgia, serif;">resisting relative lateral motion. -two things it depends on
 * Coefficient of Friction** is the ratio of friction to normal force.

The level of friction that different materials exhibit is measured by the coefficient of friction. The formula is µ = f / N, where µ is the coefficient of friction, f is the amount of force that resists motion, and N is the normal force. Normal force is the force at which one surface is being pushed into another. If a rock that weighs 50 newtons is lying on the ground, then the normal force is that 50 newtons of force. The higher µ is, the more force resists motion if two objects are sliding past each other.

-The Force of Static Friction keeps a stationary object at rest -Once the Force of Static Friction is overcome, the Force of Kinetic Friction is what slows down a moving object When the object is still, and you have to move it, you have to use coefficient of static friction. If the object were moving then coefficient of kinetic friction is applied. In other words, as soon as the object starts sliding static friction is no longer used it turns to a lower kinetic friction.