AP Physics 1 - First Semester Review

Displacement

Vector quantity; where you end up versus where you started regardless of path taken.

Distance

Scalar quantity; How far you travel. It can be the same as displacement when direction hasn't changed

Speed

Scalar quantity; How fast an object travels. Distance over time.

Velocity

Vector quantity; How fast and in what direction an object travels. Displacement over time.

Average Velocity

Total Displacement over total time. It is always ZERO on a round trip.

Acceleration

Change in velocity over a time interval.

Slope on a Position-Time or Displacement-Time graph

Average Velocity

Slope on a Velocity-Time Graph

Average Acceleration

Area on a Velocity-Time Graph

Displacement (Distance when you ignore the negative signs)

Area on an Acceleration-Time Graph

Average Velocity

Flat Slope on a Position-Time Graph

NO Motion

Flat Slope on a Velocity-Time Graph

NO acceleration (Constant v)

Vector

A quantity with magnitude (Numerical size) and direction; Can be positive or negative.

Scalar

A quantity with magnitude (Numerical size) only; Cannot be negative.

Resultant

A vector sum, including direction.

Equilibrant

A force that puts a system in Equilibrium or balance; equal to the Resultant but in the opposite direction.

Horizontal Vector Component

The part of the vector in the X plane; Vector times the cosine of the angle.

Vertical Vector Component

The part of the vector in the Y plane; Vector times the sine of the angle.

Finding the Vector angle

Tangent of the angle = Vertical component over the Horizontal component.

Projectile motion

Motion that moves in the X and Y plane under the influence of gravity.

Horizontal Component of Velocity

Constant during the entire trajectory.

Trajectory

The path travelled by a projectile.

Vertical Component of Velocity

Changes due to gravity. Decreases on the way up, Zero at the maximum height, and increases on the way down.

Relative Motion

Motion relative to a frame of reference (Example looking at a boat's motion and taking the flow of water into account)

Free-Fall

An object moving solely under the influence of gravity.

Initial Vertical Velocity

Zero on an object that is launched horizontally.

Acceleration of a Projectile

Gravity, 9.8 m/s/s, for the entire trajectory.

Force

A push or pull on a body. Measured in Newton's.

Weight

The pull of gravity on a mass; measured in Newton's.

Mass

The amount of matter in a body; measured in kilograms.

Normal Force

The force of a surface pushing back against an object. It equals weight when an object is on a flat surface and there is no force pulling up or pushing down.

Inertia

The tendency of an object to resist a change in its motion.

Newton's 1st Law

An object at rest, stays at rest; An object in motion, stays in motion, unless an unbalanced force acts on it.

Newton's 2nd Law

Acceleration is directly proportional to net force and inversely proportional to mass.

Newton's 3rd Law

For every action there is an equal and opposite reaction; forces always occur in pairs.

Parallel Force

The component of an object's weight that acts down a ramp or inclined plane; Equal to weight times the sine of the angle.

Perpendicular Force

The component of an object's weight that acts into a ramp or inclined plane; Equal to weight times the cosine of the angle. It opposes the normal force when an object is on a ramp.

Force pushing down on an object

Normal Force increases = Weight plus

Y- component of the force.

Force pulling up on an object

Normal Force decreases = Weight minus the Y- component of the force.

Net Force = ZERO

When an object isn't accelerating (Constant velocity) or is at rest.

Centripetal Force

A force that is directed toward the center of a curved or circular path.

Centripetal Acceleration

Acceleration toward the center of a curved or circular path.

Tangential Velocity

If an object is traveling in a circle it is constantly changing direction. The velocity of an object travelling in a circle is always at right angles to the centripetal force. If the centripetal force was removed this would be the direction in which the object would move; Measured in m/s.

Angular Velocity

The object's rotational speed, measured in radians per second (rad/s).

Torque

A turning or twisting force; the moment of a force; the measure of a force's tendency to produce twisting or turning and rotation around an axis.

Rotational Equilibrium

Exists only when the vector sum of all the torques acting on an object is zero.

Momentum

A measure of how hard it is to stop an object. Only moving objects have momentum.

A quantity defined as the product of the mass and velocity of an object.

Impulse

Something that changes the momentum of an object. As a measurement, it equals the objects mass multiplied by its velocity, or Force times the time interval in which it acts.

Momentum-Impulse Theorem

Impulse is equal to change in momentum. for a given change in momentum, a larger time interval will have a smaller force. reasoning behind airbags and crumple zones in cars.

Elastic Collision

A collision in which the total momentum and the total kinetic energy are conserved.

Inelastic Collision

Maximum loss of KE, objects stick together & momentum is still conserved.

Perfectly Elastic Collision

Perfectly elastic collision is defined as one in which there is no loss of kinetic energy in the collision (they bounce off each other).

Work

"Use of force to move an object; calculated as force multiplied by distance." Measured in Joules.

Mechanical Energy

The total amount of potential and kinetic energy in a system

Potential Energy

Energy stored due to an object's position or arrangement.

Kinetic Energy

The energy an object has due to its motion.

Work - Energy Theorem

Work done on a system is equal to the change in the systems energy.

Law of Conservation of Momentum

The rule stating that the total amount of momentum in a closed system is always the same.

Law of Conservation of Energy

The law that states that energy cannot be created or destroyed but can be changed from one form to another.

Newton's Law of Universal Gravitation

Every particle in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

How do airbags work?

The airbag increases the time interval over which the force acts, thereby decreasing the amount of force.

Conditions for Work

Force must be in the direction of motion and the object must move.

Power

A quantity that measures the rate at which work is done or energy is transformed.

Maximum Vector Sum

Occurs when vectors are in the same direction. The angle between them is 0 degrees.

Minimum Vector Sum

Occurs when vectors are in opposite directions. The angle between them is 180 degrees.