NUMS physics Flashcards

Question

1st, 2nd, & 3rd law of thermodynamics

Answer 1

1. energy cannot be created or destroyed 2. for a spontaneous process, the entropy of the universe increases 3. a perfect crystal at zero Kelvin has zero entropy

Answer 2

states that magnetic field (B) around a closed loop is proportional to the current (I) passing through the loop *in simple terms*: if you have a wire carrying an electric current, it creates a magnetic field around it. strength of that magnetic field depends on the amount of current flowing through the wire

Answer 3

The electric field around a charged object is related to the total charge inside an imaginary surface around it. If you know the charge inside, you can figure out how strong the electric field is.

Answer 4

**Electric Field Intensity (E)**: a measure of the strength of an electric field at any point **formula**: E= F/q q - charge F - force defined as **force per unit charge**

Answer 5

force per unit mass

Answer 6

the resistance of pure metal **increases with an increase in temperature** - b/c in pure metals, as temp increases, atoms in metal vibrate more and increased vibration causes more collisions b/w free electrons, increasing resistance - increase in pressure can also increase resistance, but effect is less pronounced than that of temp

Answer 7

- at very center of wire (r=0), magnetic field is 0 - as you move away from the center of the wire (increasing r), magnetic field increases because enclosed current is increasing - field increases linearly with r until you reach the surface of the wire so: **magnetic field inside current carrying wire varies directly with r** **outside the wire**: magnetic field decreases as you move farther with distance, (inversely proportional to r - 1/r)

Answer 8

when angle b/w magnetic field and vector area is **0º** - at 90º, magnetic field lines are parallel to the surface, not passing through it, but at 0º, they are perfectly perpendicular and passing through has something to do with the equation of magnetic flux which is B x A x cos(º) and like cos (0) =1, but cos(90) = 0

Answer 9

- is a vector quantity - units of momentum is N⋅s (SI unit is kg⋅m/s) - product of **mass and velocity** p = mv

Answer 10

slope of displacement-time graph: **velocity** slope of distance-time graph: **speed**

Answer 11

for objects that free fall under the influence of gravity alone (ignoring air resistance), they accelerate at the same rate which is acceleration due to gravity (g≈ 9.8m/s^2) - so, **mass does not matter, only height** answer: **both of these have the same velocity**

Answer 12

decreases by a factor of 4 or (1/4) because **KE = 1/2mv^2** kinetic energy is proportional to the square of velocity

Answer 13

1 radian = 57.3º 1 degree = 0.0175 radian

Answer 14

θ = s/r s = arc length (distance covered along the circumference) r = radius of the circle

Answer 15

v = rω ω = angular velocity v = linear velocity

Answer 16

**frequency of spring oscillation is inversely proportional to the square root of the mass** f∝ 1/√ m so to increase frequency by a factor of 4, you need to decrease mass by a factor of 4^2 = 16

Answer 17

**Cp**: amount of heat needed to raise the temperature of 1 mole of gas by 1°C at *constant pressure* **Cv**: amount of heat needed to raise the temperature of 1 mole of gas by 1°C at *constant volume* Since R is a positive number, Cp **must be greater** than Cv for the equation to work **Cp > Cv**

Answer 18

**capacitance**: ability of a capacitor to store electrical energy - higher capacitance = store more charge - measured in **Farads (F)** works by 2 metal plates separated by insulating material (called dielectric). when you apply voltage, one plate gets positive charge, the other gets negative charge **depends on**: - area of the plates: larger area increases capacitance - distance b/w plates: smaller distance increases capacitance - medium b/w plates (dielectric constant): higher dielectric constant (better insulating material) increases capacitance *metal type does not affect capacitance directly, mainly effects electrical conductivity, which is not a factor in the capacitance formula*

Answer 19

**R = r** R: resistance of the load r: resistance of the source (internal system) - if the resistances match up perfectly, get more flow going *think*: in many systems, balancing 2 quantities often gives best performance

Answer 20

3.6 x 10^6 or 3.6 MJ (megajoules)

Answer 21

**temp**: higher temps means molecules move faster which means transmit sound waves more quickly **density of medium**: density affects how easily sound waves can travel through a substance **moisture (humidity)**: moist air (has water vapor) so less dense than dry air (which contains N and O particles), allowing sound waves to travel faster in moist air *pressure does not have any effect b/c density & pressure change in a way that they cancel each other out*

Answer 22

equal to **100 rads** or **1 J/kg** or J kg^-1 - SI init of absorbed radiation dose, represents amount of radiation absorbed per unit mass of a substance

Answer 23

**same nature**: action and reaction forces are of the same type (e.g., both are gravitational, both are electrical, etc.)n bp **same line**: they act along the same line but in opposite directions **different bodies**: they always act on different bodies, not on the same body. (ex. if you push on the wall, wall pushes back on you but they are acting on different bodies) *action and reaction cannot cancel each other out b/c they don't act on the same body, can only cancel when act on the same body*

Answer 24

When two objects move in opposite directions, their **relative velocity is the sum** of their individual velocities. - ex. 2 buses moving across each other in opposite direction - their velocities relative to each other is both their individual velocities added together

Answer 25

**formula: 2π √M/k** M = mass, k = constant but really just take the square root of the mass and multiple by the given time period so: period of oscillation given = 1 sec mass of spring = 16M √16 = 4 x 1 = 4 sec

Answer 26

equals watt, which is the unit of power

Answer 27

both have the same dimensions which are Newtons per ampere-meter or N/A*m

Answer 28

remain the same - in general, increase/decrease in pressure has no effect on sound

Answer 29

**move straight** if it enters **perpendicular** to the magnetic field liens, it will deflect toward the north/south

Answer 30

product of **force and time** - also equal to the **change in momentum**

Answer 31

force x displacement = **work done** (J or Nm) force x velocity = **power** (W or J/s) force x acceleration - F = ma force x time = **impulse** (change in momentum - Ns)

Answer 32

Work = Force x Distance so in this case, 10N x 250m = 2500 J *since all work is done by gravity going straight down, can neglect that part otherwise would have to do cos of that angle and multiply it by everything*

Answer 33

U = -GMm/r G = gravitational constant M = mass of Earth m = mass of object r = distance from the center of the Earth if Earth contracts to half size, radius divided by 2 and because inversely proportional, gravitational potential energy would double

Answer 34

θ = s/r θ = angular displacement s = arc length (distance covered along circumference) r = radius of the circle

Answer 35

speed of the wave (v) = frequency (f) x wavelength (λ) **wavelength has to be in meters and waves in Hz or waves/second**

Answer 36

speed of the wave (v) = frequency (f) x wavelength (λ) 1 cm -> 0.1 m waves -> 100/sec so 0.1 m x 100 sec = 1 ms^-1

Answer 37

horizontal velocity = constant vertical velocity = 0

Answer 38

device that increases or decrease voltage (emf) in an alternating current (AC) circuit works on the principle of **electromagnetic induction**

Answer 39

small electronic component that acts like a **switch or amplifier** in circuits - it can turn a current on or off in a circuit, just like a light switch or can take a small electrical signal and make it bigger - are found in almost every electronic device, from computers to smartphones, because they help control and amplify the flow of electricity

Answer 40

states that induced EMF (voltage) in a circuit is **proportional** to the rate of change of the magnetic flux through the circuit so: - The faster you move the magnet or the stronger the magnet is, the more electricity you generate. - If you change the strength of the magnetic field or move the magnet faster, you make more electricity. **electromagnetic induction**: process by which a chaining magnetic field induces an electric current in a conductor - if you move a magnet near a wire, you can create electricity in the wire

Answer 41

**magnetic flux**: how many magnetic field lines pass through a certain area. more lines pass through = stronger the magnetic flux depends on: **strength of magnet**: stronger magnets have more lines **area**: bigger areas can catch more lines **angle**: angle b/w magnet and wire affects how many lines go through

Answer 42

**time period**: time period it takes for one complete wave to pass a given point (secs) - if you know frequency, you can find the time period using: T = 1/f **frequency**: number of waves that pass a point in one second (Hz)

Answer 43

changing in frequency or wavelength of a wave in relation to an observer moving relative to the wave source **approaching source**: if source of wave is moving towards observer, waves are compressed, causing frequency to increase (higher pitch or tone) **receding source**: if source is moving away from observer, waves are stretched out, causing frequency to decrease (lower pitch or tone)

Answer 44

type of repetitive, back and forth motion that follows a specific pattern - ex. swinging pendelum or a mass on a spring **restoring force**: always acts in the opposite direction to the displacement and is proportional to the displacement **angular frequency** (ω)** ω = 2π f **energy**: total energy in SHM is constant, with kinetic and potential energy transforming into each other.

Answer 45

**zero** because no work is done on objects moving in circular motion W = F x d x cos(angle)

Answer 46

2π radian or 6.28

Answer 47

**stationary waves**: waves that seem to be standing wall, formed by interference of 2 waves traveling in opposite directions with the same frequency and amplitude **nodes**: points on the wave where there is no motion (zero displacement). at nodes, all energy is **potential** (max displacement) (the area where the two waves intersect) **antinodes**: when the waves are away from each other (the tops of them). at antinodes, wave alternates kinetic and potential energy - when passes through equilibrium position = **kinetic only**

Answer 48

outer wheels

Answer 49

violet - blue - green - yellow - red moving towards right in this order, wavelength increases so **red has highest wavelength** but frequency decreases b/c inversely proportional

NUMS physics Flashcards

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