AP Physics Facts

Position-vs-Time Graphs

time is on the x-axis, position is on the vertical axis; slope corresponds to velocity; motion is uniform only if the slope is a straight line

Velocity-vs-Time Graphs

time is on the x-axis, velocity is on the vertical axis; slope corresponds to acceleration; motion is uniform only if the slope = 0; area under the curve = displacement

Vector Addition Process

compute the horizontal and vertical components of each vector using trig and known quantities in order to add together like parts of separate vectors for a net sum

Free Fall Acceleration

the acceleration due to gravity = -g = -9.8m/s^2

Parabolic Motion

composed of two independent motions: uniform motion at a constant velocity along the horizontal axis and free-fall motion in the vertical direction

Uniform Circular Motion

objects have a centripetal acceleration pointing from their position along the circle straight towards the center point

Newton's First Law

an object at rest will stay at rest and an object in motion will stay in motion, moving at a constant velocity along a straight line, unless acted upon by a force (inertia)

Weight

force caused by gravity that pushes objects vertically downward at a constant acceleration

Spring Force

basic contact force involving a spring that can either push or pull on an object based on the displacement of the spring from its equilibrium position and the elasticity of the spring

Tension Force

basic contact force exerted when a wire or string pulls on an object; always runs in direction of string

Normal Force

contact force exerted by a surface against which an object is pressing to push the object back up and maintain equilibrium

Friction

resistant force that occurs when one object slides across another; always parallel to the surface the object is sliding over; due to microscopic characteristics of surface; kinetic friction occurs when an object is in motion, static friction keeps an obje

Drag

resistive force on objects moving through fluids; always acts opposite to the motion of the object

Thrust

force caused by the rapid expulsion of large amounts of exhaust gas; acts opposite the direction the gas is released

Newton's Second Law

force causes acceleration; that acceleration is directly proportional to the magnitude of the force and inversely proportional to the mass of the object that the force is acting on

Newton's Third Law

for every action, there is an equal and opposite rection

Equilibrium

static equilibrium occurs when an object is at rest, because no net forces or torque is acting on it; dynamic equilibrium occurs when an object is in uniform motion, also because no net forces or torque is acting on it

Apparent Weight

the magnitude of the contact force that supports an object; the sum of the force(s) pointing in the opposite direction of the force of weight

Relationship between Kinetic Friction and Speed

kinetic friction does not depend on speed; it is a constant value based on the mass of the moving object and the smoothness of the surface on which it travels

Terminal Speed

terminal speed is the speed at which the force of gravity and the force of air resistance acting on a falling object are equal, causing it to continue falling at a constant speed until it hits the ground

Tension around Pulleys

the magnitude of the tension in a string is unchanged when moved across a massless frictionless pulley, but the tension force does change directions

Angular vs Regular Measurements

angular position, velocity, and acceleration deal with change in the position of an object around a circle, real or in a graphical representation of motion; regular measurements of position, velocity, and acceleration deal with the actual distance travele