Gravity and Friction Review

Flashcards based on the Gravity and Friction review worksheet covering Sir Isaac Newton's Law of Universal Gravitation, mass versus weight, falling objects, and air resistance.

According to Sir Isaac Newton's Law of Universal Gravitation, what two factors determine the strength of gravitational attraction between objects?

The mass of the objects and the distance between the objects.

How does an object's mass affect its gravitational pull?

Objects with more mass exert a greater gravitational pull.

How does increasing the distance between two objects affect the force of gravity between them?

As the distance between two objects increases, the force of gravity decreases.

What is the main difference between mass and weight regarding location in the universe?

Mass remains the same no matter where you go in the universe, while weight depends on gravity and does not remain the same in other places.

How do you convert mass in pounds to kilograms based on the worksheet?

Divide the mass in pounds by $2.2$, because $1\text{ kg} = 2.2\text{ lbs}$.

Who disproved Aristotle's belief that heavier objects fall faster by dropping cannonballs from the leaning Tower of Pisa in the 1600's?

Galilee Galileo.

What was the result of Galilee Galileo's experiment dropping cannonballs of different masses from the leaning Tower of Pisa?

They hit the ground at the same time.

On Earth, what factor mainly determines the rate at which an object falls?

The surface area of the object.

Why do objects with more surface area fall slower on Earth?

Because they have more friction with the air.

What is friction with the air called?

Air resistance.

Why do all objects fall at the same rate on the moon?

Because there is no air on the moon.

What force causes all falling objects to accelerate as they fall?

Gravity.

What is the acceleration due to gravity on Earth?

$9.8\text{ m/s/s}$ or $9.8\text{ m/s}^2$.

How does the acceleration due to gravity on the moon compare to that on Earth?

It is less than on Earth because the moon has less mass.

How does the acceleration due to gravity on Jupiter compare to that on Earth?

It is greater than on Earth because Jupiter has more mass.

What occurs when an object reaches terminal velocity during a fall?

The upward force of air resistance equals the downward force of gravity, so the object no longer picks up speed and its velocity remains constant for the rest of the fall.

Gravity is an _________ and noncontact force. This means it ______ objects without touching them.

attractive; pulls

Gravity does not ______ on objects

push

All objects that have mass have ________. The larger the mass the _______ the gravitational pull.

gravity; greater

Gravity between two objects depends not only on the mass of the object but also the _________ the objects

distance between

The farther apart the objects, the ___________ the pull of gravity.

weaker

The earth’s ___________ causes all objects to accelerate towards the center of the earth at a rate of __________

gravitational pull; 9.8 m/s/s

When an object falls, the air gets in the way and __________.  This friction with the air is called __________.

slows it down; air resistance

What is the reason why objects fall at different rates?

Air resistance

Objects with (greater/less) surface area fall slower because they experience _______ air resistance.

greater; more

What is it called when the upward force of air resistance balances (equals)   the downward force of gravity, and the falling object stops accelerating and continues to fall at a constant velocity.

terminal velocity (Net force=0)

Friction is a force that ________ motion. This means it slows things down. There can be so much friction between two objects that the two objects will not move at all.

opposes

Sometimes friction is good like walking and sometimes it is bad like in games that you want to glide farther such as hockey, ice skating, air hockey, rollerskating, etc.

there’s no answer but a question for this might be on the test.

An object that orbits the earth does so because of _______

the Earth's gravity

what would happen to an orbiting object if gravity disappears?

the object would fly off into space

Mass and Weight are NOT the same thing.  Your mass is just the ______ that makes you up.  Weight is a force that depends on the _________.  You will weigh ______ on planets with more gravity.

matter; pull of gravity; more

How do you calculate your weight?

Convert your mass in pounds to kg by dividing your pounds by 2.2. and multiply your mass in kg by the acceleration due to the earth’s gravity ( 9.8 m/s/s).