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61 Cards in this Set

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How does velocity differ from speed?
Velocity-Vector
(includes direction)
Speed-Scalar
How does average velocity differ from istantaneous velocity?
average is taken over period of time; instantaneous is one given moment
What is acceleration?
rate at which velocity changes
Can you accelerate at a constant speed?
yes, while turning
What does it mean to be in free fall?
only force on you is gravity
What is the acceleration of an object in free fall?
9.8 m/s(squared)
What is the initial velocity of a dropped object?
0
When is the equation d=vt used? When is d=(1/2)at(squared) used?
d=vt-when speed is constant
d=(1/2)at(squared)-speed is changing, when initial velocity is zero
What is the difference between a vector and scalar?
vector-measurement w/ direction
scalar-measurement w/o direction
Why doesn't gravity slow a ball down that's rolling on the ground?
gravity is a vertical force, does not affect horizontal motion
Does gravity affect the hoizontal motion of a projectile?
No
If you drop a bullet and fire a bullet from a horizontal rifle simutaneously, which bullet will hit the ground first? Why?
same time, b/c same initial vertical velocity
What is Newton's first law? (inertia)
an object at rest will stay at rest, an object in motion will stay in motion unless acted upon by an outside force
How does intertia relate to seatbelts? Headrests?
seatbelts-object in motion will stay in motion(deccelerating)
headrests-object at rest will stay at rest(accelerating)
What are mass and weight? Describe units, vector/sclar, and key differences.
Mass-scalar, kg, measure of an object's inertia or matter in an object
Weight-vector, N, gravitational pull on an object
Why do scientists prefer mass to weight?
mass is universal
What is equilibrium? What is the net force?
when net force is 0 N
Is an object at a constant velocity in equilibrium?
Yes
What is the upward force that keeps a book on a table in equilibrium?
normal/support force
What is Newton's second law?
net force on an object causes acceleration that is proportional to force and inversely proportional to the mass; same direction as net force
What is the relationship between force and acceleration?
directly proportional
What is the relationship between mass and acceleration?
inversely proportional
What is friction?
resistive force of two objects' grip
What is the relationship between force and pressure?
directly proportional
What is the relationship between area and pressure?
inversely proportional
Summarize Newton's third law.
every force causes an equal and opposite reaction force
What is momentum?
measure of an object's forward progress

p=mv
What is the momentum of an object at rest?
0
Is momentum conserved?
Yes
What type of collision causes two objects to hook together?
completely inelastic
What is work? Give the units.
changing an object's energy, joules
Can someone do work on an object at rest?
No
What is the relationship between power and time?
inversely proportional
What are the two types of mechanical energy?
kinetic and potential
What is kinetic energy?
energy of motion
When an object doubles its speed, what happens to the kinetic energy?
quadrupoles
Is energy conserved?
Yes
How is energy lost?
heat because of friction and air resistance
What is the difference between rotational and tangential speed?
rotational-rotations/time
tangential-distance/time
What is centripetal?
inward
What happens if CG extends over support base?
object topples
What does universal gravity mean?
all objects in the universe exert forces on each other
Why doesn't the earth crash into the sun due to gravity?
great tangential speed
Why was Cavendish's discovery important?
enabled the discovery of the mass of the earth
Why do objects in orbit float?
in free fall
What is an atom?
substance w/ same # of protons
What are the four phases of matter?
plasma, gas, liquid, solid
What is the SI unit of charge?
coulomb (C)
What is coulomb's law?
F=[kq(1)q(2)]/d(squared)
Give an example of a solid w/ a crystal structure?
ice, salt, sugar, etc...
Give an example of an amorphous solid?
glass
What is the relationship between volume and density?
inversely proportional
Does liquid pressure push down on an object only from above?
no, all sides
How can a dam holding back a small pond be under more pressure than a dam holding back Lake Superior?
if it is deeper
Is upward pressure on the bottom of an object the same as downward pressure on the to?
no, upward pressure is greater because pressure increases w/ depth
What is buyant frce?
upward force on immersed obct
What is the buoyant force equal to? What principle is this?
weight of fluid displaced; Archimedes'
Does buoyant force increase with depth?
no
Can you change a liquid's volume or density?
no, it cannot be compressed like a gas
What is Boyle's law?
pressure and volume of a gas are inversely proportional

P(i)V(i)=P(f)V(f)
What is Bernouilli's Priciple?
as speed of fluid increases, pressure decreases