PHY130 Exams 1-4 Vocab

These flashcards cover key concepts in physics related to waves, motion, and equilibrium.

Resonance

Pushing a system at its natural frequency to get a big response

Frequency

The number of repeats in an interval of time

A wave

A moving disturbance that transports energy

A transverse wave

A wave where the disturbance is perpendicular to the direction of energy transport

Constructive interference [in the context of waves]

When two waves in the same space add to make a bigger wave

Destructive interference

When you add two waves so that peaks line up with troughs and you get a smaller wave as a result

Explain briefly what the doppler effect is for a source moving towards you

When a source is moving towards you, the wavelength gets compressed and therefore the frequency is greater.

What is meant by the “Period” for simple harmonic motion (SHM)

The time it takes for the motion to repeat exactly

What does the moment of inertia of an object tell you?

How hard it is to get an object to change its rotation

What are the conditions for an object to be in static equilibrium

Net force and net torque are both zero

distance (d)

a scalar that measures the how far something traveled with no direction

displacement (∆x)

a vector pointing from the initial to final position of an object (how far and which way)

average velocity

the displacement over a period of time divided by that period of time

a vector quantity

acceleration

the change per unit time in how fast and which way an object is going

the rate at which the velocity changes

instantaneous speed

magnitude of the instantaneous velocity

gives how fast an object is going at a given instant in time

instantaneous velocity

the displacement per unit time calculated over a very small time interval ∆t about the time we care about

The average velocity over a very small time-window around the time we care about. A vector that points in the direction the object is going at that instant.

average speed

the distance traveled divided by the time taken to travel that distance

spending more time at the top of their path

The object’s y-component of velocity is zero at the top of their path, because they change y-direction. This means that their y-velocity is small at the top, so it takes longer to travel any deltay then at the bottom, where their y-component of velocity is large

If you toss something straight upward it spends more time in traveling the last 5 cm to reach the top of its path, then the 5 cm right after you release the object. Explain, briefly, why that is the case

Because the velocity and acceleration point opposite directions on the way up the object is slowing down. At the top when it changes direction the velocity is zero, in the y-direction, for an instant. Near the top the magnitude of the velocity is therefore the smallest, so it takes the longest to cover a fixed distance.

Normal force

Force perpendicular to a surface that keeps objects from occupying the same space

An inertial reference frame

A choice for where to measure position from where Newton’s 1st law holds

Tension

force transmitted by a rope, cable, or chain

static friction force

A force that keeps objects from starting to slip over each other.

Weight force

Force due to the mass of the Earth pulling on the mass of an object

Kinetic friction force

Force along a surface that fights slip once an object is already slipping

Centripetal acceleration

Acceleration towards the center of a turn that changes the direction of the velocity without changing the magnitude

A conservative force

A force where the work done by that force is independent of the path

Potential energy

The energy due to the arrangement of objects

Impulse

The average force times the duration the force acts.

Also the change in momentum

kinetic energy

the scalar energy associated with motion

An internal force

a force whose 3rd law pair also acts on an object in our system

Work

A transfer of energy between systems or types