Unit 7: Uniform Circular Motion, Gravity, Torque

uniform circular motion

objects moving in circular paths at a constant speed

period

the time it takes to complete one full revolution at a constant speed (time/revs)

frequency

the number of revolution per second (revs/time)

Hertz (Hz)

metric unit for frequency

centripetal acceleration

acceleration of an object moving in a circular path at a constant speed caused by the changing direction of the object's velocity

centripetal

"center-seeking"

centripetal force

net force acting toward the center of an object's circular path

Law of Universal Gravitation

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

field

an area around an object that affects other objects

gravitational field

an area around a mass that affects other masses

field vectors

arrows used to represent the direction and strength of a field

Kepler's 1st Law

Each planet travels in an elliptical orbit around the sun and the sun is at one of the focal points.

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.

torque

quantity that measures the ability of a force to rotate an object around an axis

Newton-meter (Nm)

metric unit for torque

lever arm

distance between the applied force and the point of rotation

rotational equilibrium

state in which the net force and the net torque on an object is zero