Physics Flashcards

Flashcards generated from lecture notes for exam review.

What is a physical quantity?

A measurable quantity that can be expressed as a numerical value and a unit.

What are derived units?

A derived unit can be expressed in terms of products or quotients of base units.

What does it mean for an equation to be homogeneous?

The units of both sides of the equation should be the same.

What characterizes a scalar quantity?

A scalar quantity has a magnitude only. It is completely described by a certain number and a unit.

What characterizes a vector quantity?

A vector quantity has both magnitude and direction. It can be described by an arrow whose length represents the magnitude of the vector and the arrow-head represents the direction of the vector.

What is accuracy in measurement?

Accuracy refers to the degree of agreement between the result of a measurement and the true value of the quantity.

What is precision in measurement?

Precision refers to the degree of agreement (scatter, spread) of repeated measurements of the same quantity OR the size of the smallest division (on the measuring instrument).

How are systematic errors characterized?

There is a constant error in all readings. It cannot be eliminated by averaging. Introduces a y-intercept on the graph. If systematic error is small, measurement accurate.

How are random errors characterized?

The readings scattered (equally) about the true value. The error can be reduced by averaging. When random error is small, measurement precise.

Define distance.

Total length covered by a moving object.

Define displacement.

Total length covered by a moving object in a specific direction.

Define speed.

Distance travelled per unit time.

Define velocity.

Distance travelled per unit time in a specific direction/ rate change of displacement.

Define acceleration.

Rate change of velocity with respect to time.

What is the formula relating final velocity (v), initial velocity (u), acceleration (a), and time (t)?

v = u + at

What is the formula for displacement (s) given initial velocity (u), time (t), and acceleration (a)?

s = ut + ½ at2

What is the formula relating final velocity (v), initial velocity (u), acceleration (a), and displacement (s)?

v2 = u2 +2as

What is the formula for displacement (s) given initial velocity (u), final velocity (v), and time (t)?

s =1/2 (u+v)t

What is Newton's First Law?

An object continues in a state of rest or uniform motion in a straight line unless a net (external) force acts on it.

What is Newton's Second Law?

The rate of change of momentum of a body is directly proportional to the resultant force acting on the body, and the momentum change takes place in the direction of the resultant force.

What is Newton's Third Law?

When object X exerts a force on object Y, object Y exerts a force of the same type that is equal in magnitude and opposite in direction on object X. The two forces ALWAYS act on different objects and they form an action- reaction pair.

Define mass.

The property of a body that resists change in motion.

Define weight.

The force of gravitational attraction (exerted by the Earth) on a body.

Define linear momentum.

The product of the object’s mass and velocity. i.e. p = mv

Define force.

Force is defined as the rate of change of momentum. i.e. F = 𝒎(𝒗−𝒖) 𝒕 = ma

State the principle of conservation of momentum.

When objects of a system interact, their total momentum before and after interaction are equal if no resultant (external) force acts on the system. OR The total momentum of an isolated system is constant. i.e. m1 u1 + m2 u2 = m1 v1 + m2 v2 if resultant F = 0 {for all collisions }

What is an elastic collision?

Collision at which the momentum, kinetic energy and total energy are conserved. Relative speed of approach is equal to relative speed of separation.

What is an inelastic collision?

Collision at which only the momentum and total energy conserved. Kinetic energy is not conserved. It may be converted into other forms of energy such as sound and heat energy.

Define center of gravity.

It is defined as that point through which the entire weight of the object may be considered to act.

Define couple.

A couple is a pair of forces which tends to produce rotation only.

Define moment of a force.

The product of the force and the perpendicular distance of its line of action to the pivot.

Define torque of a couple.

The product of one of the forces of the couple and the perpendicular distance between the lines of action of the forces

State the conditions for equilibrium.

1. The resultant force acting on it in any direction equals zero. 2. The resultant moment about any point is zero.

Define density.

Mass per unit volume.

Define pressure.

Force per unit area, where the force acts perpendicularly to the area.

What is the formula for hydrostatic pressure?

p = g h where = density, g = acceleration due to gravity and h = height

Define upthrust.

An upward force exerted by a fluid on a submerged or floating object; arises because of the difference in pressure between the upper and lower surfaces of the object.

Define work done.

Work done by a force is defined as the product of the force and displacement (of its point of application) in the direction of the force. i.e. W = F s

Define efficiency.

The ratio of (useful) output energy of a machine to the input energy.

Define power.

Work done per unit time

Define spring constant.

Force per unit extension. i.e. k = F/e

State Hooke's Law.

Extension is proportional to load provided the limit of proportionality is not exceeded.

Define Strain energy

Energy stored in a body due to change in shape.

Define Strain.

extension/ original length i.e. e/l

Define Stress.

force/cross-sectional area i.e. F/ A

Define Young Modulus

ratio stress to strain i.e. E = Fl / Ae

Define Elastic deformation

An elastic deformation is the change of shape / size / length / dimension when a (deforming) force is removed, returns to original shape / size.

Define Plastic deformation

The object does not return to its original shape when the force applied is removed.

What is displacement in wave motion?

Position of an oscillating particle from its equilibrium position in a specified direction.

What is amplitude in wave motion?

The maximum magnitude of the displacement of an oscillating particle from its equilibrium position.

What is period in wave motion?

Time taken for a particle to undergo one complete cycle of oscillation.

What is frequency in wave motion?

Number of oscillations per unit time of the source/of a point on the wave/of a particle.

What is wavelength in wave motion?

For a progressive wave, it is the distance between any two successive particles that are in phase, e.g. it is the distance between 2 consecutive crests or 2 troughs.

What is the wave front?

A line or surface joining points which are at the same state of oscillation, i.e. in phase, e.g. a line joining crest to crest in a wave.

What is the relationship between speed (v), frequency (f), and wavelength (λ) of a wave?

v = fλ

Define progressive wave.

A wave which results in transfer of energy from one place to another without the transfer of matter.

Define Intensity of a wave, I

It is defined as the rate of energy flow per unit time {power} per unit cross- sectional area perpendicular to the direction of wave propagation. I = Power/ πr2

Define transverse wave.

A wave in which the oscillations of the wave particles are perpendicular to the direction of the propagation of the wave.

Define longitudinal wave.

A wave in which the oscillations of the wave particles are parallel to the direction of the propagation of the wave.

Define Doppler effect.

A change/difference in the observed/ apparent frequency when the source is moving relative to a stationary observer.

List the properties of electromagnetic waves.

are transverse waves consist of electric and magnetic fields oscillate at right angles to each other and to the direction in which the wave is travelling. show all properties common to wave motions; reflected, refracted, diffraction, superposition travel in the vacuum at the same speed, 3.0 x 108 ms-1 .

Define Polarisation .

vibration of particles in a wave is confined in one direction in the plane normal to direction of propagation. Only transverse waves can be polarized.

State the Principle of superposition

When two or more waves of the same type meet at a point, the resultant displacement of the waves is equal to the vector sum of their individual displacements at that point.

Define Stationary wave

A stationary wave is formed when two progressive waves of the same frequency, amplitude and speed, travelling in opposite directions are superposed.

Define Node

A point along the standing wave where the wave has zero (minimum) amplitude.

Define Antinode.

A point along the standing wave where the wave has maximum amplitude.

Define Diffraction.

It refers to the spreading {or bending} of waves when they pass through an opening {gap}, or round an obstacle (into the “shadow” region).

Define Interference

When two (or more) waves meet at a point there is change in overall intensity/displacement.

Define Constructive interference

When two (or more) waves arrive at a point in phase, a large amplitude of vibration is produced.

Define Destructive interference

When two (or more) waves arrive at a point in anti-phase, the resultant amplitude of vibration is a minimum.

Define Coherent

Waves of the same frequency and constant phase difference.

Define Path difference

The difference in distance from each source to a particular point.

Define Electric current

Electric current is the rate of flow of charge carriers.

Define Electric charge.

Electric charge Q passing a point is defined as the product of the (steady) current at that point and the time for which the current flows, i.e. Q = I t

Define Coulomb

product of ampere and second.

Define Potential difference

Potential difference between two points in a circuit is the energy converted per unit charge from electrical to other forms of energy. V = W/q

Define Volt

joule per coulomb

Define Resistance.

Resistance is defined as the ratio of the potential difference across a component to the current flowing through it, i.e. R = V/I

Define Ohm

volt per ampere

State Ohm’s Law

The current through a metallic conductor is proportional to the potential difference across the conductor provided the temperature remains constant.

Define Resistivity

R =l/ A {for a conductor of length l, uniform x-sect area A and resistivity } Resistivity is defined as the resistance of a material of unit cross-sectional area and unit length.

Define EMF

It is defined as the energy transferred/converted from non-electrical forms of energy into electrical energy when unit charge is moved round a complete circuit. i.e. EMF = energy transferred per unit charge, i.e. E =W/ Q

Define Internal resistance

Internal resistance is the resistance to current flow within the power source. It reduces the potential difference (not EMF) across the terminal of the power supply when it is delivering a current.

State Kirchoff’s first law

The sum of the currents entering any point (or junction) in a circuit is equal to the sum of the currents leaving that same point. This law conveys the conservation of charge.

State Kirchoff’s second law

The algebraic sum ofthe e.m.f.s round a closed loop in a circuitis equal to the sum of p.d.s in that same loop.

What is the overall resistance of resistors in series?

RT = R1 + R2 + R3

What is the overall resistance of resistors in parallel?

1/RT = 1/R1 + 1/R2 + 1/R3

Describe the nuclear model of an atom

The nucleus consists of protons and neutrons, and is surrounded by a cloud of electrons.

What are quarks?

Quarks are fundamental particles that make up other subatomic particles such as protons and neutrons.

What are Antiquarks?

The equivalent antiparticle of the quark is the anti-quark. These are identical to quarks except with opposite relative charges

What are hadrons?

Hadrons are the group of subatomic particles that are made up of quarks.

What are baryons?

Baryon (3 quarks OR 3 anti quarks)

What are mesons?

Meson (quark and anti-quark pair)

What are Leptons?

Leptons are a group of fundamental (elementary) particles. This means they are not made up of any other particles (no quarks)

Define Isotopes

Isotopes: are atoms with the same proton number, but different nucleon number {or different no of neutrons}