Chapter 12 Section 2 Gravity
weight
A measure of the force of gravity on an object
Explain why free-fall acceleration near Earth's surface is constant.
Near Earth's surface, the distance between the object that is falling and the center of Earth does not change very much. Thus, the force given by the law of universal gravitation depends only on the mass of the object that is falling.
Explain why the gravitational acceleration of any object near Earth is the same no matter what the mass of the object is.
Newton's second law shows that acceleration depends on both force and mass. A heavier object experiences a greater gravitational force than a lighter object. The extra mass of the heavy object exactly compensates fot the additional gravitational force. Since F=ma or a=f/m), if F is increased at the same rate as m, then a remains the same.
Name the two components that make up orbital motion, and explain why objects stay in orbit.
Orbital motion has two components - horizontal and vertical. Horizontal motion propels the object forward and vertical free fall pulls the objectdownward toward the center of gravity of the larger mass.
State the Law of universal gravitation, and use examples to explain how changes in mass and changes in distance affect gravitational force.
The Law of universal gravitation says the force of gravitational attraction is proportional to the attracting masses and inversely proportional to the square of the distance between the masses. If you make the mass of one or both of the attracting masses larger, than the force will be larger. The gravitational attraction between Earth and a satellite gets smaller as the satellite move further away from Earth.
terminal velocity
The constant velocity of a falling object when the force of air resistance is equal in magnitude and opposite in direction to the force of gravity
projectile motion
The curved path an object follows when thrown or propelled near the surface of the Earth.
The force between a planet and a spacecraft is 1 million newtons. If the spacecraft moves to half of its original distance from the center of the planet, what will the force be.
The force of gravity is inversely proportional to the square of distance. Since the distance is made.twice as close, the force of gravity will be four times as great (the square of 2), or 4 million N.
Explain why your weight would be less ob the moon than on earth even though your mass would not change.
The moon's mass is much smaller than earth's mass. Since the force of gravitational attraction between two objects depends on the mass of both objects, the force of gravitational attraction between you and the moon would therefore be smaller than the force between you and the Earth.
free fall
The motion of a falling object when the only force acting on it is gravity
