Physics 1: Force and Net Force Mechanics — 100 Flashcards

100 practice flashcards covering key concepts from the lecture notes on force, motion, electricity, magnetism, waves, optics, thermodynamics, and modern physics.

What is Newton's First Law of Motion (Law of Inertia)?

An object at rest or in uniform straight-line motion remains in that state unless acted on by an external unbalanced force; mass measures inertia.

What is inertia?

The natural tendency of an object to resist changes in its state of rest or motion.

Differentiate scalar and vector quantities.

Scalar quantities have magnitude only; vector quantities have both magnitude and direction.

What was Aristotle's view on natural motion?

Aristotle believed an object required a force to remain in motion; natural state was rest.

State Newton's Second Law.

Acceleration is produced by an external net force; F = m a (a = F/m).

What is centripetal acceleration?

a_c = v^2 / r, the acceleration toward the center of circular motion.

What is centripetal force?

F = m a_c = m v^2 / r, the net force toward the center of curved motion.

State Newton's Third Law.

For every action, there is an equal and opposite reaction; F1 = -F2.

What is voltage?

The work required to move a unit charge between two points; V = W/q.

What is Ohm's Law?

V = I R; voltage equals current times resistance.

What is electrical power?

Power is the rate of energy transfer, P = IV (also P = I^2 R or P = V^2 / R).

In a series circuit, how does current behave?

The same current flows through all components (I_series is constant).

How is total resistance in a series circuit calculated?

R_s = R1 + R2 + R3 + …

In a series circuit, how is voltage distributed?

Vin = V1 + V2 + V3 + …

In a parallel circuit, what is the voltage across each resistor?

The same voltage V is across each resistor.

In a parallel circuit, how does current split?

Total current is the sum of the branch currents: I_in = I1 + I2 + I3 + …

How is equivalent resistance computed in a parallel network?

1/R_p = 1/R1 + 1/R2 + 1/R3 + …

What happens if a component burns out in a series circuit?

Current becomes inactive; the circuit is open in that path.

What happens if a component burns out in a parallel circuit?

Only the affected branch stops; other branches continue.

What are the two magnetic poles called?

North and South.

What is the meaning of the North pole?

North-seeking; it points toward geographic north.

What is the meaning of the South pole?

South-seeking; it points toward geographic south.

What does the Law of Poles state?

Like poles repel and unlike poles attract.

What is a magnetic dipole?

A magnet with two poles; it has a North and a South pole.

What is a magnetic field?

A set of imaginary lines indicating the direction of magnetic force; a vector field.

What is the source of magnetism in materials?

Moving and spinning electrons create magnetic fields.

Who discovered that a compass needle is deflected by a current-carrying wire?

Hans Oersted.

What happens to the magnetic field around a wire as current increases?

The magnetic field becomes stronger with greater current.

What does polarization of light prove?

Light is a transverse wave; polarization demonstrates this.

What does a Polaroid film do?

Acts as a polarizer, allowing only light with a certain polarization plane to pass.

What is a converging lens?

A lens that focuses parallel rays toward a focal point.

What is a diverging lens?

A lens that causes rays to spread apart, seeming to originate from a focal point on the same side.

What is diffraction?

The bending of waves around openings or obstacles when their size is comparable to the wavelength.

What is the principle of superposition?

When two waves meet, they add or subtract; can reinforce (constructive) or cancel (destructive).

What are the two main types of interference?

Constructive and destructive interference.

What are the three primary electric charges and what are their signs?

Electrons are negative; protons are positive; neutrons are neutral.

State Coulomb's Law.

F = k q1 q2 / r^2; force between two point charges.

What is k in Coulomb's Law?

k = 9.0 x 10^9 N m^2 / C^2.

What is the basic nature of charge in atoms?

Objects can be positively charged (loss of electrons) or negatively charged (gain of electrons).

State Newton's Law of Universal Gravitation.

F = G m1 m2 / r^2; G = 6.67 x 10^-11 N m^2/kg^2.

What is work?

W = F d; work is energy transferred by a force over a distance.

What is the SI unit of work?

Joule (J).

What is kinetic energy?

KE = 1/2 m v^2.

What is potential energy due to gravity?

PE = m g h.

What does the conservation of energy state?

Ek + Ep remains constant in an isolated system.

What is power?

Power is the rate of doing work; P = W/t (or P = F d / t).

What is a heat engine?

A device that converts heat into work by transferring heat from a hot reservoir to a cold reservoir.

What does the 2nd law say about heat flow?

Heat cannot spontaneously flow from cold to hot; 100% conversion of heat to work is impossible.

What is a heat pump?

A device that uses work input to transfer heat from a low-temperature reservoir to a high-temperature reservoir.

What is the Third Law of Thermodynamics?

Absolute zero is unattainable; zero kelvin is the lower limit of temperature.

What is entropy?

A measure of disorder; in isolated systems it never decreases; the universe’s entropy increases.

What is the Zeroth Law?

If two systems are in thermal equilibrium with a third, they are in thermal equilibrium with each other.

What are the two main categories of mechanical waves by particle motion?

Longitudinal and transverse.

What demonstrates that light is a transverse wave?

Polarization experiments show light is transverse.

What is the Doppler effect?

Apparent change in frequency due to relative motion between source and observer; blue shift when approaching, red shift when receding.

What is a standing wave?

A stationary waveform formed by interference of waves traveling in opposite directions.

What are nodes and antinodes?

Nodes have zero displacement; antinodes have maximum displacement.

What is the fundamental frequency and overtones?

Fundamental frequency f; first overtone f2; higher overtones at multiples of f.

What is the Law of Reflection?

The angle of incidence equals the angle of reflection; incident, reflected, and normal lie in the same plane.

What is Snell's Law?

n1 sin θ1 = n2 sin θ2; describes refraction at a boundary.

What is the index of refraction?

n = c/v; ratio of light speed in vacuum to speed in the medium.

What is a spherical mirror?

A mirror formed from a spherical surface with radius R and center of curvature C.

What is the principal axis in a spherical mirror?

A line drawn through C to the mirror surface.

What is the vertex (V) in a spherical mirror?

Point where the principal axis intersects the mirror surface.

What is the focal length in a spherical mirror?

f = R/2.

What are object distance (Do) and image distance (Di)?

Do is the object distance from the vertex; Di is the image distance from the vertex.

What is a real image?

An image formed by converging rays that can be projected on a screen.

What is a virtual image?

An image formed by diverging rays that cannot be projected on a screen.

What is ray diagramming?

Solving image locations by tracing light rays graphically.

What is the energy expression for a hydrogen electron En?

En = -13.60 eV / n^2.

What is the binding energy of hydrogen in the ground state (n=1)?

-13.60 eV.

What does Planck's quantum theory state?

Energy quantization: E = h f for oscillators; energy depends on frequency.

What is Planck's constant value?

h = 6.63 x 10^-34 J s.

What does the Bohr model propose about hydrogen?

A single electron orbits a single proton in discrete energy levels.

What is the Bohr principal quantum number?

n = 1, 2, 3, … describe energy levels.

What is the radius of a hydrogen orbit (r_n)?

r_n = 0.053 nm n^2.

What happens when an electron transitions to a lower energy level?

A photon is emitted.

What happens when an electron transitions to a higher energy level?

A photon is absorbed.

What does the acronym LASER stand for?

Light Amplification by Stimulated Emission of Radiation.

What is stimulated emission?

An excited atom emits a second photon when struck by a photon of the same energy.

What is photon energy in terms of frequency?

E = h f; energy of a photon is proportional to frequency.

What is the relationship between speed, wavelength, and frequency for light?

c = λ f; the speed of light equals wavelength times frequency.

What is the order of the electromagnetic spectrum from longest to shortest wavelength?

Radio, Microwave, Infrared, Visible, Ultraviolet, X-ray, Gamma.

What is the value of the speed of light, c?

Approximately 3.0 x 10^8 m/s.

What portion of the EM spectrum is visible to the human eye?

Visible light, between infrared and ultraviolet.

What are the three regions of sound frequency?

Infrasonic (

What is sound intensity a measure of?

The rate of energy transfer per unit area; units W/m^2.

What is pitch?

Perceived highness or lowness of a sound, related to frequency.

What is latent heat?

Heat associated with a phase change (not a temperature change).

Latent heat of fusion (Lf) for water?

Lf = 80 kcal/kg.

Latent heat of vaporization (Lv) for water?

Lv = 540 kcal/kg.

What are the three forms of heat transfer?

Conduction, Convection, Radiation.

What is conduction?

Transfer of heat through a solid by molecular interactions.

What is convection?

Transfer of heat through a fluid by motion of the fluid.

What is radiation?

Transfer of heat via electromagnetic waves.

What does the first law of thermodynamics relate?

Energy added to a system equals the change in internal energy plus work done.

What is the relation between temperature scales Celsius and Kelvin?

K = C + 273; absolute zero is 0 K.

What are the ice and steam points of the Celsius scale?

Ice at 0°C; steam at 100°C.

What are the ice and steam points of the Fahrenheit scale?

Ice at 32°F; steam at 212°F.

How do you convert Celsius to Fahrenheit?

F = (9/5)C + 32.