Chapter 3- Forces Flashcards
What is Newton’s 2nd Law?
The more mass an object the more force it will take to make it accelerate.
What is the formula for newton’s 2nd law.
F=ma
What is friction?
A force that can stop an object in motion
What does friction want to do?
wants stop sliding motion
What are microwelds?
the source friction
How do microwelds form?
When bumps come in contact
When are microwelds the strongest?
when a larger force pushes them together
How do you break microwelds?
force must be applied
What is static friction?
the force that prevents two forces from sliding past each other
What else do I need to know about static friction?
static friction is where a force is canceling your push
What is a force that isn’t strong enough to break microwelds?
Static Friction
What is sliding friction?
a force that opposes motion of two surfaces sliding past one another.
What is sliding friction caused by?
microwelds continually braking then forming again
What do you have to do to keep something moving during sliding friction?
you have to constantly be pushing it
What is rolling friction?
A force between a rolling object and the surface it rolls on
What happens if static friction acts over a deformed area?
it causes rolling friction
What is air resistance?
opposes the motion of objects through the air
What direction does air resistance act in?
the opposite direction to a motion of an object through the air
What would happen if air resistance didn’t exist?
All object would fall at the same speed.
What does air resistance on an object depend on?
speed, size, and shape
What is one thing Air resistance doesn’t depend on?
Mass
What is terminal velocity?
the downward force of gravity causing and object to accelerate
What happens when an object is falling very fast?
the upward force of the air resistance increase
the net force of an object is when what happens?
there’s a balanced downward force of gravity
What does terminal velocity depend on ?
size,shape and mass
what is gravity?
an attractive force between any two objects
What are the two things gravity depends on?
mass of the objects and distance between them.
how does the force of gravity increase?
mass of either object increases, or the objects move closer together.
Is gravity one of the four basic forces?
Yes
What are 3 of the other basic forces?
electromagnetic force, strong nuclear force, and weak nuclear force.
where do the 2 nuclear forces work?
on particles in the nuclei of atoms.
What causes Electricity and magnetism?
electromagnetic force.
What is the formula for gravitational force?
gravitational force= mass x acceleration(due to gravity)
Can gravity ever be zero?
no matter how far apart 2 objects are gravity never goes to zero.
what is it called when all forces except gravity can be ignored?
free fall
How fast is the acceleration of an object in free fall near the earths surface?
9.8 m/s squared
What is weight?
The gravitational force exerted on an object.
Is weight a force?
yes
What is mass?
a measure of the amount of matter an object contains.
If you throw a ball horizontally what will it do?
It will go in a curve (gravity)
if you drop a ball straight down and one as hard as possible horizontally will it fall at the same rate?
Yes
When a ball goes around in a circle what change of direction is the velocity going in?
toward the center.
What is acceleration toward the center of a curved path called?
centripetal acceleration
When a ball has centripetal acceleration what is the direction of the net force?
The center of the curved path.
What is the net force exerted toward the center of the curved path called?
Centripetal force.
What is one thing that centripetal force works for?
when a car is turning it keeps it from falling over
What is newton’s 3rd laws?
for every action there is an equal or opposite reaction.
what is an example of newton’s 3rd law?
Trampoline
What happens when a rocket exerts gasses on the ground.
newton’s 3rd law and the rocket will go up as it pushes down on the ground.
What is momentum?
the product of mass and velocity.
What is the opposite of momentum?
Inertia
Is momentum a force?
no
What is the symbol for momentum?
P
How can momentum change?
mass, velocity, or both change.
Can momentum be transferred into different objects?
Yes
If a ball is still what is its momentum?
there is none, it isn’t lost or created.
what is weightlessness?
When you have practically no gravity pulling you down (you feel weightless
