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.

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.

A person is in a railway car without any windows. What test can the person perform to determine whether the car is at rest or is moving at constant velocity? (a) toss a ball horizontally (b) drop a ball vertically (c) let two masses collide on the floor (d) There is no experiment the person can do to determine whether the car is at rest or moving at constant velocity.

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.

Why do people not observe time dilation in their daily experiences? (a) Time dilation only occurs on railroad cars, not in automobiles. (b) People need to be travelling backward for time dilation to activate. (c) Typical terrestrial speeds are much too low to notice the effects of time dilation. (d) Typical terrestrial speeds are much too high to notice the effects of time dilation.

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?

Consider the properties of inertial and non-inertial frames of reference. (a) How does an inertial frame of reference differ from a non-inertial frame of reference? (b) Give two examples of each type of frame of reference.

A process takes place in a given amount of time. (a) Does the process seem to take longer for an observer moving relative to the process, or for an observer at rest with respect to the process? (b) Which observer measures the proper time of the process?

The mass of a particle travelling at nearly the speed of light increases beyond its rest mass.

Einstein originally wanted to call his model "the special theory of reference frames.