Variable Relationships
As distance separating the objects increases, does the force increase, decrease, or stay the same?
decrease
What is the difference between mass and weight?
mass is how much matter something has-this value DOES NOT change no matter where in the universe you are.
weight is the force value that depends on your mass and gravity-this value WILL change depending on where you are in the universe
The strength of the force of gravity between two objects depends on which two factors?
masses of objects and their distance apart (from their centers of mass)
What type of pattern does an orbit follow?
Uniform Circular Motion
If Earth's mass was increased, with no change in radius, would your weight increase, decrease, or stay the same?
increase; gravitational force increases
The measure of the pull of gravity on an object is the objects' what?
weight
If a force of gravity exists between all objects, why do we not feel ourselves being pulled toward tall buildings in our vicinity?
relatively speaking, the masses of a tall building and of us are very small compared to the masses of planets, stars, and moons
What provides the centripetal force in an orbit?
Gravitational Force
A 10-kg brick and a 1-kg book are dropped. The acceleration of gravity on the 10-kg brick is what compared to the 1-kg book?
Equal
What is G? (what does it stand for-the actual value, what is it used for?)
G is the universal gravitation constant, 6.67 x 10-11 N*m2/kg2; it is used to calculate the force acting on two objects with mass
True or False:
A force of gravity only exists if there is a planet, moon, or sun involved. For example, there is no force of gravity acting between me and my pencil.
False-there is a force of gravity (attractive force) acting between any two objects, even if it is really small
Why are astronauts weightless?
They are always being pulled to the Earth and falling, but they have so much speed that they never hit the ground.
If you are closer to a star, to maintain a perfect circle, do you need to be faster or slower?
faster
What is Newton's Law of Gravitation? Hint: it is a formula
Fg=Gm1m2/r2
The gravitational pull the moon has on the earth compared to the gravitational pull the earth has on the moon is
equal and opposite; newton's third law of action and reaction forces applies here
What would happen to the moon's motion if its tangential velocity were reduced to zero?
it would come crashing into the earth because the only force acting on it would be gravity, and without the tangential velocity propelling it forward, gravity would pull it into the earth.
More
What does Kepler's 3rd Law help us with?
Comparing the period and distance of an object's orbit around a mass.
Does the smaller mass matter in the properties of the orbit? (hint: look at the equations we have learned.)
No. For example, to orbit Earth, it doesn't matter if it's the moon or a small marble, it will orbit the same.
What keeps the moon in perfectly circular orbit around the Earth?
A perfect tangential velocity and the centripetal force supplied by gravity.