Physics H Midterm Walz

Projectile Motion

Motion in two dimensions with a vertical and horizontal component.

Trajectory of a Projectile

Parabolic path of a projectile in motion.

Horizontal Velocity of a Projectile

Constant velocity in projectile motion.

Resultant

Combination of vertical and horizontal components in two-dimensional motion.

Newton's First Law of Motion

An object at rest remains at rest, and an object in motion continues in motion with constant velocity, unless acted upon by an external force.

Inertia

The tendency of an object not to accelerate or resist change.

Force

An action exerted on an object which may change the object's state of rest or motion.

Unit of Force

Newton (N), defined as the force required to accelerate a one kg mass 1 m/sec squared.

Equilibrium

State of an object at rest or moving with constant velocity where net force is zero.

Newton's Second Law of Motion

The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

Net Force Equation

Net Force = mass x acceleration.

Newton's Third Law of Motion

For every action, there is an equal and opposite reaction.

Weight

Mass of an object times the acceleration due to gravity; a force that depends on location.

Normal Force

The force that acts perpendicular to an object.

Friction

A restrictive force that keeps an object from moving.

Static Friction

Friction that is equal to and opposite in direction to the applied force when the object is not moving.

Kinetic Friction

The frictional force acting on an object in motion.

Coefficient of Friction

The ratio of the force of friction to the normal force.

Work

The product of the force applied in the direction of displacement and the amount of displacement.

Work Equation

Work = force x displacement x cosine of the angle between them.

Unit of Work

Measured in newton meters, which is a Joule (J).

Kinetic Energy

The energy of an object in motion, calculated as KE = ½ mass x velocity squared.

Work-Kinetic Energy Theorem

The net work done on a body equals its change in kinetic energy.

Power

The rate at which work is done or energy is transferred.

Power Equation

Power = Work/time, measured in Joules/seconds or Watts.

Gravitational Potential Energy

Energy of an object at rest, calculated as PE = mgh.

Elastic Potential Energy

Energy available for use when a deformed elastic object returns to its original shape, calculated as EPE = (1/2) x spring constant x distance squared.

Impulse-Momentum Theorem

Force x time interval = change in momentum.

Momentum

Defined as the product of mass and velocity, represented by the symbol p.

Momentum Units

SI units are kilogram-meters per second.

Conservation of Momentum

The amount of momentum always remains the same.

Perfectly Inelastic Collision

Occurs when two objects collide and move together as one mass.

Kinetic Energy in Perfectly Inelastic Collision

Not conserved; some kinetic energy is changed to heat energy, sound energy, etc.

Elastic Collision

Two objects collide and return to their original shape, with no loss in kinetic energy.

Most Collisions

Are neither elastic nor perfectly inelastic.

Tangential Speed

Speed of an object along an imaginary line drawn tangent to its circular path.

Tangential Acceleration

Acceleration due to change in speed of an object moving in a circular path.

Centripetal Acceleration

Acceleration directed towards the center of the circular path.

Centripetal Force

Force directed towards the center of the circular path.

Gravitational Force

The force of attraction between two objects.

Orbital Velocity

Velocity of a satellite moving at the same velocity as the planet it orbits.

Newton's Law of Universal Gravitation

Describes the gravitational force between two masses.

Gravitational Field

A field force that does not require contact between two masses.

Torque

Measures the ability of a force to rotate an object around an axis.

Lever Arm

Perpendicular distance from the axis of rotation to a line drawn along the direction of the force.

Unit for Torque

Newton Meter.

Efficiency of a Machine

Ratio of Work(output) to Work(input).

Kepler's 1st Law

Each planet orbits around the sun in an elliptical orbit.

Kepler's 2nd Law

An imaginary line drawn from the sun to any planet sweeps out equal areas in equal time intervals.

Kepler's 3rd Law

The square of a planet's orbital period is proportional to the cube of the average distance between the planet and the sun.

Uniform Circular Motion

When an object rotates around a fixed point with a constant speed.

Net Force in Circular Motion

Directed towards the center of the circle, called centripetal force.