Skills & Kinematics
The slope of a velocity time graph is...
Acceleration
Define each of Newton's Three Laws.
N1L: An object in motion stays in motion and an object at rest stays at rest, unless acted on by an unbalanced force.
N2L: Fnet=ma (the acceleration of an object is proportional to its net force, and inversely proportional to its mass).
N3L: For every action there is an equal and opposite reaction.
Work is...
(hint: two things)
1) force times the displacement
2) the change in energy
What is the difference between resistance and resistivity?
Resistance is the ability to limit current
Resistivity is a property of the wire's material, describes how conductive a material is
What is the principle of superposition?
When two or more waves combine
Waves that are in phase (have amplitudes with the same sign) add together.
Waves that are out of phase (have amplitudes of opposite sign) subtract.
If you can't remember the units for something, what should you do?
Use the formula!
The net force acting on an object always acts in the same direction as...
the object's acceleration
Write an equation for the conservation of energy of a ball that is dropped a distance
Ug top = K bottom
When asked to describe the brightness of a lightbulb, you need to determine the...
power of the bulb
How do you determine the harmonic of a standing wave?
Count the antinodes (crests or troughs)
Describe the type of acceleration if the direction of an object's velocity and displacement are opposite
Slowing down
Given a projectile that is thrown straight up, describe the following:
(ex. does it increase, decrease, stay the same? what is it? etc.)
a) vertical acceleration
b) horiztonal acceleration
c) vertical velocity
d) horizontal velocity
a) constant (a=g)
b) zero
c) decreases as it rises, v=0m/s at the top, then increases as it falls
d) constant
You should think "Conservation of Momentum" and use its equation anytime what occurs?
a collision! (aka one object moving towards and striking another object)
Describe the voltage, current, and resistance in a series and a parallel circuit.
Series:
VT = V1 + V2 + V3
IT = I1 = I2 = I3
Req = R1 + R2 +R3
Parallel:
VT = V1 = V2 = V3
IT = I1 + I2 + I3
(1/Req) = (1/R1) + (1/R2) + (1/R3)
As an object emitting a constant sound approaches you, what happens to the frequency and wavelength?
As an object emitting a constant sound recedes from you, what happens to the frequency and wavelength?
Approaching:
wavelength decreases, frequency increases
Receding:
wavelength increases, frequency decreases
When is the appropriate time to use v=d/t ?
When an object is moving at constant speed (a = 0 m/s2)
What is the centripetal force in the following cases:
a) satellite orbiting a planet
b) car driving in a circle
c) rollercoaster on a loop
d) mass on a string twirled in a circle
a) Fg
b) Ff
c) FN
d) FT
Write out the equations for the following collisions:
1) two objects collide and bounce apart
2) two objects collide and stick together
1) m1vo1 + m2vo2 = m1vf2 + m2vf2
2) m1vo1 + m2vo2 = (m1+m2)vf
Write out Newton's second law for rotational motion
torque = moment of inertia * angular acceleration
When a mass attached to a spring is oscillating, what can be said about its speed and energy at maximum displacement, minimum displacement, and equilibrium?
Minimum displacement: v = 0, all potential energy
Equilibrium: constant vmax, all energy is kinetic
Maximum displacement: v = 0, all potential energy
A ball rolls off a table. An identical ball is dropped from the same height at the same time. Which will hit the ground first?
They will hit at the same time. Time it takes to fall depends on acceleration (aka: g), initial vertical velocity (vo = 0 m/s in both cases), and height dropped from (same in both cases)
What are the first steps in solving a pulley problem?
1) Choose a coordinate system (which way do you want to be positive, negative, etc.)
2) Write out your net force equations for the vertical direction (y) and the horizontal direction (x)
3) Remember: if masses are connected with the same rope, they experience the same FT
Fnet = 0
a = 0
net torque = 0
(the object is balanced, object is at rest or moving at constant speed, etc.)
For a rolling object, how does the speed at the top, the speed at the center, and the speed at the bottom of the object compare?
Top: twice the speed at the center
Center: speed at the center is the speed of the object itself
Bottom: v=0
What are the three types of standing waves?
Strings: fundamental harmonic:
L = 1/2wavelength
Open pipe:
fundamental harmonic: L = 1/2wavelength
Closed pipe: fundamental harmonic:
L = 1/4wavelength