Gabor stands on a cart that moves with a constant velocity. In his frame of reference, he tosses a ball vertically up and down. Lutaaq stands on the ground nearby. She also tosses a ball vertically up and down with respect to her frame of reference. (a) Explain what the motion of Gabor's ball looks like from Lutaaq's frame of reference. (b) Explain what the motion of Lutaaq's ball looks like from Gabor's frame of reference.

A spacecraft measures $70 \mathrm{~m}$ in length when stationary. As the spacecraft travels at a speed close to the speed of light, what length will be measured by a stationary observer? (a) slightly more than $70 \mathrm{~m}$ (b) slightly less than $70 \mathrm{~m}$ (c) exactly $70 \mathrm{~m}$ (d) less than $10 \mathrm{~m}$

Identify which laws of conservation are applicable for objects moving at speeds near the speed of light.

A spacecraft passes you at a speed near the speed of light. Inside the spacecraft is a metre stick aligned in the direction of motion of the spacecraft. Describe the appearance of the length of the metre stick from your perspective on Earth.

What quantity must be invariant between all inertial reference frames?

Two identical, very precise clocks are started at the same time. One clock is taken on a trip at a speed close to the speed of light, and the other is left at rest on Earth. When the travelling clock is returned to Earth, it shows that $1 \mathrm{~h}$ has passed. Describe the time that has passed on the Earth clock.

What fields of physics are unified in Maxwell's equations?

The rest energy of an object is always less than the classical kinetic energy of the same object.

When two protons and two neutrons fuse into a helium nucleus, energy is emitted and mass remains constant.

When a particle doubles its speed from $0.45 c$ to $0.90 c$, the relativistic energy will increase by more than a factor of four.

An object has rest mass $m$. If the object's relativistic momentum is $4 m c$, then its speed must be $4 c$.

The twin paradox is proof that special relativity is just an exercise for the mind and cannot really happen.

Francois is travelling at a speed of $0.95 \mathrm{c}$ on a railway car, which Francois has measured as $25 \mathrm{~m}$ in length. Soledad, who is located on the ground near the railway tracks, arranges for two small explosions to occur on the ground next to the ends of the railway car. According to Soledad, the two explosions occur simultaneously, and she uses the burn marks on the ground to measure the length of Francois's railway car. According to Francois, do the two explosions occur simultaneously? If not, then according to Francois, which explosion occurs first?

The chemical energy released by $1.00 \mathrm{~kg}$ of the explosive TNT equals about $4.20 \times 10^6$ J. Determine the rest mass, when converted, that produces a rest energy identical to the amount of energy released by TNT.