PHYSICS 121 FINAL EXAM REVIEW QUESTIONS WITH
VERIFIED ANSWERS
How many standard balloons can fit into a minivan? - answers - about 200
A standard helium balloon is of the order of a foot across. The inside of a minivan is
about 5 feet across by 4 feet high by 8 feet long. That is a volume of about 200 cubic
feet. Probably only about 2/3 of that can be used for balloons, so 200 is probably too
high, but it is closer than any of the other answers.
Carrying bucket at constant speed, what work is done? - answers - none, it's a constant
speed so no change in kinetic energy
Also it wasn't lifted up, so the gravitational energy didn't change since gravitational force
was perpendicular to the displacement
Unstable equilibrium point is where - answers - where the potential energy is at a
maximum
Neutral equilibrium is where? - answers - where it is flat no curvature
How to take a dot product? - answers - i*i - j*j = 1 number
Net work is equal to what?? - answers - change in kinetic energy.
Think about v2 in the kinetic energy theorem and remember that !
Conservative forces include:
Nonconservative forces include:
Definition - answers - gravity conservative, electric elastic,
Air resistance nonconservative, friction applied tension push and pull
Conservative forces have no net work over a closed loop, equal work between points
irrespective of path, always has potential energy function
Nonconservative forces do more work over longer path distances and do have net work
over closed loops
Point of stable equilibrium definition - answers - a point where a force will always bring it
back to that no matter what, like a ball in a bowl it will always make it back to the
bottom, or a stretchy spring will always make it back to its resting state.
What is impulse?
What is momentum equation? - answers - impulse is change in momentum
Momentum is mass times velocity
, In collisions, what is always conserved and what might not be? - answers - momentum
is always conserved even if the collision isn't head on
Kinetic energy sometimes is and sometimes isn't
Cross product is perpendicular to ? - answers - both vectors crossed!
Cross two vectors with only i and j or whatnot - answers - magnitude a * magnitude b *
sin theta between them
Angular acceleration:
Equation
And theory - answers - a(not fish) = r * w^2
A(fish/alpha) is net torque/moment of inertia
Net torque/ moment of inerita
Net torque / moment of inertia!!!
Also tangential velocity is propritional to the radius
We gotta divy up potential energy from top of ramp amoung what? - answers -
translational and rotational motion
So sliding object gets there first if something else was rolled
Elastic collisions conserve what? - answers - kinetic energy
What is stopping time? Equation - answers - change in momentum (impulse) / force
stopping it
Power is what formula - answers - power = force times velocity
Power = change in energy/ change in time
Elastic potential energy - answers - u = 1/2 k x^2
Circular motion with constant speed requires what kind of force? - answers - a net
inward force, a centripetal inward acceleration
A body is falling through the air.
When do bodies reach constant velocity in general?
When will that falling body reach constant velocity?
What quantity is air resistance proportional to?
Terminal velocity is related to mg how? - answers - when the forces on it balance net
force is zero
When the weight is equal to air resistance
Proportional to v^2
Terminal velocity has v = sqrt( 2 mg /stuff)
Newtons first law - answers - if there are no external forces (not zero net force, it means
no external forces) it will stay at rest or stay at the velocity forever.
VERIFIED ANSWERS
How many standard balloons can fit into a minivan? - answers - about 200
A standard helium balloon is of the order of a foot across. The inside of a minivan is
about 5 feet across by 4 feet high by 8 feet long. That is a volume of about 200 cubic
feet. Probably only about 2/3 of that can be used for balloons, so 200 is probably too
high, but it is closer than any of the other answers.
Carrying bucket at constant speed, what work is done? - answers - none, it's a constant
speed so no change in kinetic energy
Also it wasn't lifted up, so the gravitational energy didn't change since gravitational force
was perpendicular to the displacement
Unstable equilibrium point is where - answers - where the potential energy is at a
maximum
Neutral equilibrium is where? - answers - where it is flat no curvature
How to take a dot product? - answers - i*i - j*j = 1 number
Net work is equal to what?? - answers - change in kinetic energy.
Think about v2 in the kinetic energy theorem and remember that !
Conservative forces include:
Nonconservative forces include:
Definition - answers - gravity conservative, electric elastic,
Air resistance nonconservative, friction applied tension push and pull
Conservative forces have no net work over a closed loop, equal work between points
irrespective of path, always has potential energy function
Nonconservative forces do more work over longer path distances and do have net work
over closed loops
Point of stable equilibrium definition - answers - a point where a force will always bring it
back to that no matter what, like a ball in a bowl it will always make it back to the
bottom, or a stretchy spring will always make it back to its resting state.
What is impulse?
What is momentum equation? - answers - impulse is change in momentum
Momentum is mass times velocity
, In collisions, what is always conserved and what might not be? - answers - momentum
is always conserved even if the collision isn't head on
Kinetic energy sometimes is and sometimes isn't
Cross product is perpendicular to ? - answers - both vectors crossed!
Cross two vectors with only i and j or whatnot - answers - magnitude a * magnitude b *
sin theta between them
Angular acceleration:
Equation
And theory - answers - a(not fish) = r * w^2
A(fish/alpha) is net torque/moment of inertia
Net torque/ moment of inerita
Net torque / moment of inertia!!!
Also tangential velocity is propritional to the radius
We gotta divy up potential energy from top of ramp amoung what? - answers -
translational and rotational motion
So sliding object gets there first if something else was rolled
Elastic collisions conserve what? - answers - kinetic energy
What is stopping time? Equation - answers - change in momentum (impulse) / force
stopping it
Power is what formula - answers - power = force times velocity
Power = change in energy/ change in time
Elastic potential energy - answers - u = 1/2 k x^2
Circular motion with constant speed requires what kind of force? - answers - a net
inward force, a centripetal inward acceleration
A body is falling through the air.
When do bodies reach constant velocity in general?
When will that falling body reach constant velocity?
What quantity is air resistance proportional to?
Terminal velocity is related to mg how? - answers - when the forces on it balance net
force is zero
When the weight is equal to air resistance
Proportional to v^2
Terminal velocity has v = sqrt( 2 mg /stuff)
Newtons first law - answers - if there are no external forces (not zero net force, it means
no external forces) it will stay at rest or stay at the velocity forever.
