U6 Special Relativity Revision

The Michelson–Morley experiment established that

• there is no observable æther wind at the surface of Earth.
• the æther moves at the speed of light, c, as Earth travels in its orbit.
• the æther is an elastic fluid that streams over Earth.
• Earth does not move with respect to the Sun.
• none of these

Which of the following is not a consequence of special relativity?

• Moving objects appear shorter in length (thinner) than stationary objects.
• Time appears to move at a different rate for objects moving relative to each other.
• Mass and energy are the same thing: if you increase an object’s energy, you also increase its mass.
• Nothing is certain; everything is relative.

Which of the following statements about special relativity is FALSE?

• An assumption of special relativity is that the laws of physics are the same in all inertial reference frames.
• An assumption of special relativity is that the speed of light is the same in all reference frames.
• An assumption of special relativity is that space and time are part of the same thing: spacetime.
• An assumption of special relativity is that the laws of the physics are the same in all ‘constant velocity’ reference frames.

The term ‘relativistic’ refers to effects that are most easily

• measured by stationary observers only.
• observed when objects travel near the speed of light.
• observed when objects move backward in time.
• observed when any object moves.

An object moves in relation to an observer. As the object moves faster, the observer perceives the object to be

• longer
• shorter
• slower
• the same regardless of speed

This expression $\frac{1}{\sqrt{1-\frac{v^2}{c^2}}}$   represents

• time dilation

• the relativistic (Lorentz) factor

• length contraction

A rocket containing astronauts is flying through space.

• The faster it travels, the shorter it appears to people on board the ship.
• The faster it travels, the longer it appears to people on board the ship.
• Regardless of speed, the ship appears the same contracted length to people on board the ship.
• Regardless of speed, the ship appears uncontracted in length to people on board the ship.

If the mass of an object changes, what will also change?

• Its spin
• Its charge
• Its energy
• The speed of light

A clock, designed to tick each second, is moving past you at a uniform speed. You find the moving clock to be

• ticking slowly
• ticking quickly
• accurate
• running backward

An astronaut travels out toward a star. In the inertial frame of the star, the astronaut steers directly toward the star and moves at constant speed.

The astronaut can determine that she is in motion by:

• the slowing down of on-board clocks.

• the contraction of on-board metre sticks.

• her increase in mass.

• the increase in her heart rate.

• none of these