Syllabus Definitions
Calculations
Cross-topic Qs
ReTRieVAL pRAcTIce
Tobar Trivia
100
Normal Force
The force acting along an imaginary line drawn perpendicular to the surface.
100
A 5.2 kg object sits on a 45o incline and is motionless.
Calculate the magnitude of friction acting on the object.
equal and opposite to parallel force
36 N
100
A laser has a power output of 30 mW and emits light with a wavelength of 650 nm.
How many photons does this laser emit per second?
9.8x1016
100
Define Specific Heat Capacity
The ammount of energy required to change the temperature of 1 kg of a substance by 1 K (without phase change).
100
When was Mr Tobar born?
27/04/1996
200
Antiparticle (plus give an example)
A particle with the same mass, but opposite charge and/or spin to the corresponding matter particle.
E.g positron and electron
200
Calculate the momentum of a photon with a frequency of 5.3x1014 Hz
1.17x10-27 kgm/s
200
A student is considering how to levitate a thin 1.0 m long metal rod in a strong magnetic field of 1.2 T. The current flowing through the rod will be 2.3 A.
Calculate the maximum possible mass of the rod.
0.282 kg
200
A single resistor is connected to a power supply, the power dissipated by this circuit is P.
Explain how the power dissipated would change if a second, identical resistor was connected in parallel.
Resistance halves.
Voltage is the same, so current doubles.
P = VI, so the power dissipated doubles.
200
What town/region did Mr Tobar grow up in?
Accept either:
Murwillumbah (aka Murbah/Murbs)
OR
Tweed / Tweed Valley
300
Faraday's Law
A law stating that when the magnetic flux linking a circuit changes, an electromotive force (emf) is induced in the circuit that is proportional to the rate of change of the flux.
300
Alice is traveling in a spaceship at 0.69c. On her watch the journey takes 4.20 years.
Bob remains on earth and also times her journey. Determine how long the journey takes according to Bob's measurements.
t0 = 4.20
bob's time is t = 5.8 years
300
A pith ball is a very small, lightweight object that readily picks up electric charge. A pith ball with a mass of 75x10-6 kg is suspended by a string attached to a charged plate. There are 2.00x1012 electrons on it and the electric field strength between the charged plates is 95.0 NC-1.
Calculate the angel between the string and the charged plate.
tan(\theta) = F_E/(mg)
\theta = 2.37^o
300
Calculate the critical angle for a beam of light leaving a diamond (n = 2.54) and entering air.
sin(c) = 1/2.54
c = 23.18 degrees
300
Mr Tobar's brother was published in Nature this year for a paper in theoretical physics related to the standard model where he proposed an experiment.
What was the experiment?
His paper proposes an experiment that would essentially be the photoelectric effect but for gravitational waves.
400
Lenz's Law
The direction of an induced current always opposes the change in the circuit or magnetic flux that produces it.
400
The 20 cm rod pictured below is moved at a speed of 5 cm/s into the position shown.
Calculate the magnitude of the emf induced in the rod.
0.002 V
400
A metal cylinder is located in a uniform magnetic field. The work function of the metal is W.
Photons with an energy of 2W strike the side of the cylinder, liberating photoelectrons which travel perpendicular to the magnetic field in a circular path. The maximum radius of the path is 3.4 cm.
If the photon energy is doubled, what is the maximum radius of the new path?
5.89 cm
400
Calculate the binding energy of a Iodine-131 nucleus. Give your answer in MeV.
Relevant atomic masses:
Proton: 1.00727647u
Neutron: 1.008665u
Iodine-131: 130.9061246 u
Mass defect: 1.15539831u
1.91858386 x10^-27 kg
Energy: 1.72672547 x10^-10 J
1077 MeV
400
What discovery in Physics was Mr Tobar's brother published in the news for?
He discovered that time travel without paradoxes is mathematically possible.
500
Threshold Frequency
The minimum frequency of a photon that may eject an electron from a surface.
500
Calculate the magnitude and direction of the stones final velocity.
27.88 m/s
59 degrees below horizontal
500
Students wanted to calculate B field strength of Earth is Brisbane. They set up a circuit with a section of wire placed 50.0 mm above a compass.
With no current running through the circuit, the compass lined up with the Earth's magnetic field in Figure 1.
When they closed the switch, the compass needle deflected at an angle of 80 degrees to the wire as shown in Figure 2.
Calculate the strength of the horizontal component of Earth's magnetic field.
2.62x10-6 T
500
A sports car is travelling 30 ms-1 and passes a police van which is cruising at 15 ms-1. The van, accelerating at a rate of 1.2 ms-2 immediately begins to chase the car.
Calculate the time required for the van to catch the car.
25 seconds
Distance travelled is equal, using suvats for the police van and s = ut for the sports car
500
How many countries does Mr Tobar have citizenship in?
Double points if you can name all of them.
Three countries:
- Australia
- Ireland
- Ecuador