chapter 5 Flashcards
where does acceleration come from
it comes from forces
what does newtons first law say?
an object with net force will have no change in velocity (will remain at rest or maintain a constant velocity)
if you have an object at rest, what is true of the net force? are there forces still acting on the object?
the net force sums to zero. there are still forces acting on the object but since they sum to zero, the acceleration is zero
what is an agent
it is what causes the force
how is the acceleration related to force
its directly proportional
how is the acceleration related to mass
it is inversely proportional
which direction does the. acceleration point?
in the same direction of Fnet
what does newtons third law say
it says that two objects exert equal and opposite forces on each other of the same type
every force is a member of what?
it is a member of an action/reaction pair
what is equilibrium?
it is when the acceleration is zero, (Fnet=0)
what is static equilibrium
it is when the object is at rest
what is a dynamic equilibrium
it is when an object has a constant velocity
what can we do with the sum of vectors to find the Fnet?
We can break them into components and add them to find Fnet
what is the difference between mass and weight?
mass is a scaler, weight is a force that is caused by the gravitational pull of the earth
how do we calculate weight?
mass x g (acceleration of gravity)
what is apparent weight
it is our sensation of weight which is due to the contact forces supporting you
when you are moving in an elevator and accelerating upwards, how does your weight feel
it feels heavier, as the normal force of the elevator floor pushes up harder on you, you push harder on it. this creates a heavier apparent went
when does a person feel weightless and why
a person feels weightless when they are in freefall. There are no contact forces around to give a feeling of weight
what happens to the normal force as two things lose contact
it goes to zero
is the normal force always equal to the weight force?
no
when we push something with static force? what happens to the magnitude as we push harder?
the magnitude increases until we reach Usn which is the maximum static force for that material
what is true about the magnitude of kinetic friction?
it has a nearly constant magnitude
if we increase the speed of the object sliding, what happens to the magnitude of the kinetic friction?
it remains the same
what is the relationship of us (static friction) and UK (kinetic friction)
us is usually bigger than uk, it is harder to get something moving than it is to keep something moving
when you have two blocks in contact with each other, what is true of their acceleration?
they are kinematiicaly locked and move together so they have the same acceleration, same velocity, and the same displacement
if you push on a wall lightly what happens to the normal force?
if you want on a wall harder what happens to the normal force?
what does this tell us about the magnitude of the normal force?
if you push lightly, the normal force will push lightly back
if you push harder, the normal force will push harder back
this tells us that the magnitude of the normal force will be whatever it needs to be to resist penetration
what are the rules for an object to remain at static equilibrium in regards to static friction?
the direction of Fs must oppose th emotion
the magnitude of the static friction adjusts itself so the net force is equal to zero
the magnitude cannot exceed the maximum fsmax in order to stay stationary
if fs is greater than fsmax, what does it mean?
it means the object will slip and begin moving
when we have two objects in contact, what is true about their accelerations?
they have the same accelerations
if a force pulls on one end of a rope, what is true about the tension in the rope
the tension is equal to the magnitude of the pulling force
if two objects are connected by a force, what is true about the tension between the two ends of the rope?
the tension is the same on either side
what is the tension of a string when it passes over a pulley
the tension is the same on either side
the force of kinetic friction was __________ the maximum value of the static friction force
less than
