Changing Mass
A 10kg brick and a 1kg book are dropped. The force of gravity on the 10 kg brick is what compared to the 1kg book?
10 times as much
Compared to its weight on earth, a 10-kg object on the moon will weigh more, less, or the same on the moon as it does on the earth?
less
What is Newton's Law on Gravitation? Hint: it is a formula
Fg=Gm1m2/d2
How did Newton know that there was a force acting on the moon?
the moon falls toward the earth without crashing into it, the moon changes direction (this is a change in velocity which means it is accelerating), since it is accelerating we know a force must act because forces cause accelerations
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)
If Earth's mass was increased, with no change in radius, would your weight increase, decrease, or stay the same?
increase; gravitational force increases
As distance separating the objects increases, does the force increase, decrease, or stay the same?
decrease
The measure of the pull of gravity on an object is the objects' what?
weight
Gravity is actually a very small force, it only seems large when large bodies like planets are involved, TRUE OR FALSE?
True
Force of gravity is directly proportional to
mass of objects
If you double BOTH masses involved, keeping the distance constant, by what factor is the force of gravity changed by?
increased by a factor of 4
If you double the distance between two objects' centers of mass, and keep everything else constant, by what factor would the force of gravity be reduced by?
1/4
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
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 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.
Suppose the force of gravity between the earth and the moon is 100 N (just suppose). What would be the force if the mass of the moon decreased to 1/4 its original mass?
25 N
In what way is gravity reduced as the distance from the earth increases?
by inverse square of distance
How does the inverse square law relate to our formula for universal gravitation?
as the distance increases between two objects, the force of gravity decreases by a factor of the inverse square of the distance between them
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
Force of gravity is inversely proportional to
If the mass of the moon suddenly doubled, and the mass of the earth was halved, what would happen to the force of gravity acting between them?
It would remain unchanged because the the increase in mass to the moon would cancel out the decrease in mass of the earth
Suppose the force of gravity acting between two objects is 10 N. What would be the new value for the force of gravity if you doubled the distance between the two objects, and also doubled each of their masses?
10 N still
Gm1m2/d2=10 N
if we double both the masses and the distance
G(2m1)(2m2)/(2d)2 = 2*2/22=1 times the force or just 10 N
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
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
What are the two masses and one distance that go into finding your weight?
your mass, the earth's mass, the distance between you and the earth's center of gravity