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Newton’s first law
An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an external force.
Newton’s second law
Acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. It can be mathematically expressed as F = ma, where F is the net force, m is the mass of the object, and a is the acceleration.
Newton’s third law
For every action, there is an equal and opposite reaction.
Inertia
The tendency of an object to resist changes in its state of motion. It is directly proportional to an object's mass, meaning the more massive an object is, the greater its inertia.
(1st law)
Magnitude
Size of something
Direction
self explanatory
Scalar quantities
Values with only magnitude, no direction
Ex. mass, speed, distance, energy, time, temperature
Vector quantities
Values with magnitude and direction
Ex. velocity, force, acceleration, displacement
Mechanical equilibrium
All net forces equal zero
Static equilibrium
Object is in mechanical equilibrium so that it does not move
Dynamic equilibrium
Object that is in mechanical equilibrium, but at a constant velocity so that all forces equal zero.
Already in motion but since constant all forces equal zero
Normal force
Force perpendicular to the surface an object is o
Average speed
Average speed is explanatory, but the important part is it has no direction. So total distance travelled is what needs to be paid attention to.
Equation form: average speed = total distance travelled / time
Average velocity
Like average speed but it is important to know that velocity has direction. So taking that into consideration, total displacement is over time. So if I walk 2 miles left in an hour, but 3 miles right in another hour, the average velocity is 0.5 miles per hour right.
Equation form: average velocity = total displacement / time
Acceleration
The rate of which speed increases.
Equation: a = velocity final - velocity initial / time
How to calculate net force
Add all the forces acting on an object to get net force (keep in mind possible negative values from direction)
Friction Force
The force that resists motion when the surface of one object comes in contact with the surface of another.
Mew
Static friction
The friction force of an object at rest
Larger than kinetic
Kinetic friction
The friction force of an object at rest
Smaller than static or else things wouldn’t be able to move
The transfer of static friction into kinetic friction
As an object slides more, gravity can’t lock in microscopic nooks so that kinetic friction is always less
Weight
The force of gravity x mass
Weight on an incline
Same as the weight on a horizontal surface and freefall
Weight in freefall
Same as the weight on a horizontal surface and freefall
Normal force on a horizontal surface
Equal to weight of object/force acting upon it
Normal force on a incline
Only equal to the force pushing down on it and isn’t necessarily equal to the object’s weight
Normal force in freefall
0 since it is in motion and gravity is parallel to surface
Net forces on an incline or with diagonal forces
Use Pythagorean theorem to find the net force by finding the hypotenuse of vector quantities.
With an incline use the Normal and Parallel forces as the ‘legs’ or a and b to find the vector for gravity
Or do the opposite by c² - a² = b²
Momentum
It is a vector quantity that describes the motion of an object and is conserved in a closed system.
Equation: momentum=mass x velocity
Impulse
J= force x time
Relationship of momentum and impulse
change of momentum = impulse
mvf-mvi=ft
Conservation of momentum
In the absence of an external force, the momentum of a system remains unchanged.
Elastic collision
collision of stuff that bounces off each other
mvai+mvbi=mvaf+mvbf
Inelastic collision
collision of stuff that stick together
mvai+mvbi= (ma+mb) vf
Work
work it takes to do stuff
work=force x distance
Potential energy
The value for amount of stored energy, which means PE equals KE
gravitational pe: pe=mass x gravity x height
Kinetic energy
Energy of motion
ke=1/2mv²
Work energy theorem
the net work done by the forces on an object equals the change in its kinetic energy
so Work=KEf-KEi
or Work=PE
the work you do to move an object a distance is equal to its change of energy
Conservation of energy
no energy dissipates, it changes forms
Thermal energy
what most energy transfers into because of compression of atoms
Clearest way to see energy
when its being transformed
