Phys - Unit 3

Question 1

Relative Atomic Mass

Answer 1

System to measure mass where 1 = the mass of one nucleon

hydrogen has a Mr of 1

Question 2

Unified Atomic Mass Unit

Answer 2

u = 1.66x10^-27 kg = 1Da

Question 3

Molar Mass

Answer 3

System to measure mass where 1mol = number of atoms in 12g of C-12 = 6.02x10^23

Molar mass of C-12 is 12gmol^-1

Question 4

Ideal Gas Assumptions

Answer 4

NISCER

Negligible volume
Intermolecular forces
Straight lines
Constant motion
Elastic collisions
Random distributed energy & motion

Question 5

Relationship between V & p (boyles)

Answer 5

1/V ∝ p

p1V1 = p2V2

Question 6

Relationship between V & T (charlie)

Answer 6

V ∝ T

V1/T1 = V2/T2

Question 7

Relationship between p & T (gay)

Answer 7

p ∝ T

p1/T1 = p2/T2

Question 8

Circular motion velocity and acceleration

Answer 8

a = -(ω^2 x)

v = ω x

Where x = A, the velocity and acceleration are maximum

Question 9

SHM displacement, velocity and acceleration

Answer 9

x = A cos(ωt + ε)

v = -Aω sin(ωt + ε)

a = -Aω^2 cos(ωt + ε)

ε represents the phase of the system

Question 10

Period of a spring and pendulum

Answer 10

Ts = 2π√(m/k)

Tp = 2π√(l/g)

Question 11

Horizontal mass-spring system energy description

Answer 11

1/2 kA^2 = 1/2 mv^2 + 1/2kx^2

Question 12

Pendulum energy description

Answer 12

r - rcos(θmax) = hmax

mghmax = 1/2 mv^2 + mgh

Question 13

pV & Energy Equations

Answer 13

pV = nRT
= NkT
= 1/3 Nmc^2

Ek = 3/2 pV

Question 14

Deriving pV = 1/3 Nmc^2

Answer 14

1. Draw container and label all side lengths & mass and velocity of a particle
2. Momentum change & time taken between wall collisions
3. Find pV
4. Velocity can be in any direction, so find c = sqrt(vx^2 + vy^2 + vz^2)
5. On average, only 1/3 particles will travel in one plane.

pV = 1/3 Nmc^2

Question 15

Internal Energy

Answer 15

deltaU = Q - W

U = ΣEk + ΣEp, but ΣEp = 0 for ideal gases

Question 16

Mass Defect

Answer 16

Difference between predicted and actual mass of particles

Question 17

Binding Energy

Answer 17

E = [mass_defect]c^2 gives the energy needed to dissociate a nucleus into its constituent nucleons.

Question 18

Amplitude

Answer 18

Maximum displacement from equillibrium in an SHM system.

Question 19

Free / Natural Oscillations

Answer 19

Occur when an SHM system is displaced, causing it to return to equillibrium via oscillation.

Question 20

Resonance

Answer 20

Occur when a system is supplied by energy from an SHM system via a driving force.

Question 21

Resonant / Natural Frequency

Answer 21

When a system reaches a specific frequency, its amplitude is maximised.