NESA Physics Light and Special Relativity

This statement is factually incorrect and unrelated to special relativity. According to the quantum relation $E=hf$, energy is directly proportional to frequency, so energy decreases as frequency decreases.

This describes the Doppler effect rather than a fundamental postulate. While relativity influences the Doppler shift, the postulates specifically define the behavior of the speed of light, not the change in wavelength due to source motion.

This is incorrect regarding wave mechanics; frequency remains constant when light changes media, while speed and wavelength change. Furthermore, this is a concept of optics, not a postulate of special relativity.

Length contraction occurs along the direction of motion, not necessarily the height, and it is a consequence of relativistic speed rather than a barrier preventing acceleration.

Time dilation describes the relative slowing of time in a moving frame; it does not actively decrease velocity or physically prevent an object from accelerating.

As an object approaches the speed of light, its effective inertia (resistance to acceleration) increases towards infinity, making it harder to accelerate, not easier.

Total energy is conserved in the interaction, and since the final state contains the same types of particles as the initial state, the sum of the rest masses remains constant rather than decreasing.

Electrons and positrons are leptons, not baryons. Since there are no baryons in the initial or final state, the baryon number remains constant at zero.

The interaction begins with two particles (an electron and a positron) and ends with two particles (an electron and a positron), so the total number of particles remains unchanged.

This is incorrect because an accelerating object represents a non-inertial frame of reference. By definition, an inertial frame must have zero acceleration.

This is incorrect because turning a corner involves a change in direction, which means the car is experiencing centripetal acceleration. Even at a constant speed, a change in direction makes it a non-inertial frame of reference.

This is incorrect because the roller-coaster is speeding up, meaning its velocity is changing and it is accelerating. Any accelerating environment is a non-inertial frame of reference.

This calculation incorrectly treats the given 125 m as the proper length ($L_0$) and solves for the contracted length. Since the observer on the spaceship is at rest relative to it, they measure the proper length, which must be longer than the contracted length measured by the outside observer.

This answer results from omitting the square root in the Lorentz factor calculation, dividing 125 by $(1 - 0.3^2)$ instead of $\sqrt{1 - 0.3^2}$.

This value is incorrect and does not align with the standard length contraction formula. It likely results from a calculation error or misapplication of the Lorentz factor $\gamma$.

This is incorrect because relativistic momentum is a concept in special relativity, not Newtonian mechanics. In a Newtonian framework, momentum is simply defined as $p=mv$ without the Lorentz factor.

Momentum is a frame-dependent quantity, meaning its value changes depending on the observer's velocity relative to the object. It cannot be defined regardless of the frame.

In the frame where the object is stationary (its rest frame), the velocity is zero, and therefore the momentum is zero. This does not define the general concept of relativistic momentum.

An electron and positron typically annihilate to produce at least two photons in order to conserve momentum, rather than combining into a single neutral particle.

The mass of a proton or antiproton is an intrinsic property (rest mass) and is not caused by relativistic velocities.

While protons are indeed much more massive than electrons, the law of conservation of mass-energy applies, not just rest mass. The additional mass is created from the kinetic energy supplied by the accelerator.

This formula represents gravitational potential energy, where $g$ is the acceleration due to gravity and $h$ is the height above a reference point.

This is an incorrect variation that conflates the kinetic energy coefficient ($\frac{1}{2}$) with the speed of light ($c$).

This is the formula for classical kinetic energy, describing the energy of an object in motion with velocity $v$, rather than the energy equivalent of mass itself.

Incorrect. Travelling at a constant speed is insufficient because the direction could be changing (such as in circular motion), which implies acceleration. An inertial frame must travel at a constant velocity.

Incorrect. The definition of an inertial frame does not depend on its speed relative to the speed of light, $c$. A frame moving at a constant velocity close to $c$ is still a valid inertial frame.

Incorrect. The expansion of the universe is a cosmological phenomenon and does not define an inertial frame. Inertial frames are defined strictly by the absence of acceleration.