Astronomy Final

Speed =


Units: (time unit)/(distance unit) - m/s, or mi/hr

The velocity of an object is its speed, together with its associated direction.

velocity = speed with a direction

If either the speed of an object changes, or its direction changes, then its velocity changes.

An acceleration is a change in the velocity (speed &/or direction) of motion in a given amount of time.

Examples of units: m/sec², ft/sec², etc.

Something at rest is not accelerating and something moving at constant speed in a straight line isn't accelerating.  Must speed up, slow down, or change direction.

acceleration = (the velocity change)/(the time interval of the change)

A body's ability to resist changes in motion.

A measure of that inertia.

-or-

The amount of particles that make up an object.  The more particles it is made from, the greater its mass. (less accurate)

Units: grams or kilograms

In free-fall, all objects accelerate downward with the same acceleration.

A push or pull on an object.

The momentum involved when objects are spinning or circling (orbiting)

Anything that can cause a change in an object's angular momentum (twisting force)

Example: ice skater spinning around and getting faster when she pulls her arms in.

Reduces the distance between arms and the axis of rotation - increases the rotation speed.

When a planet gets closer tothe sun, decreasing the distance around which it travels, its speed increases.

The larger either of the two masses are, the stronger the force of gravity between them.  However, the farther apart they are, the bigger d (distance) is and the weaker the gravitation force.

The d changes by d² - the gravitational attraction decreases/increases by a factor of 3 x 3 = 9, not 3 + 3 = 6

The force of gravity felt by that object but the mass of an object is the amount of matter the object has.