According to the correspondence principle, (a) new theory must agree with old theory where they overlap. (b) Newton's mechanics is as valid as Einstein's mechanics. (c) relativity equations apply to high speeds while Newton's equations apply to low speeds. (d) special relativity and general relativity are two sides of the same coin.

To say that $E=m c^2$ is to say that energy (a) increases as the speed of light squared. (b) is twice as great as the speed of light. (c) and mass are equivalent. (d) equals mass traveling at the speed of light squared.

For what kind of gravitational field is Newton's law of gravity valid?

Relativity equations for time, length, and momentum hold true for (a) everyday low speeds. (b) relativistic speeds. (c) Both of these. (d) Neither of these.

Compared with the Newtonian momentum $p=m v$, the momentum of an object traveling at high speed is (a) greater. (b) less. (c) the same. (d) dependent on rest mass.

If the eye receives an average intensity greater than $1.0 \times 10^{2} \mathrm{W} / \mathrm{m}^{2}$, damage to the retina can occur. This quantity is called the damage threshold of the retina. (a) What is the largest average power (in mW) that a laser beam 1.5 mm in diameter can have and still be considered safe to view head-on? (b) What are the maximum values of the electric and magnetic fields for the beam in part (a)? (c) How much energy would the beam in part (a) deliver per second to the retina? (d) Express the damage threshold in $W/cm^{2}$.

Of all the planets, why is Mercury the best candidate for finding evidence of the relationship between gravitation and space?

The principal difference between the theory of special relativity and the theory of general relativity is in the fact that special theory of relativity deals only with the inertial reference frames i.e. uniformly moving reference frames , whereas the general theory deals also with non-inertial reference frames, i.e. reference frames subjected to the acceleration.

By the equivalence principle we know that the observations made in an accelerated reference frame are indistinguishable from observations made in a Newtonian gravitational field, meaning that the non-inertial reference frames are those arising in the cases when we actually deal with the gravity and inertial reference frames are those where we are free from the effect of gravity.

The tricky thing is to notice that in the case when you have presence of gravity, like here on Earth for example, you can always free yourself from the presence of gravity by focusing on a small $\textit{local reference frame freely falling in that gravitational field}$. Its laws would thus descend to those of special relativity.

The good check is always to ask yourself would the objects in that frame float like in free space or would be pulled to the ground like on Earth. In the first case you know you are in the realm of the special relativity and inertial reference frames, while in the second you know you are experiencing the gravity and you are in the non-inertial reference frame.

What Einstein discovered about space and time is that they (a) are separate entities. (b) are parts of one whole. (c) follow an inverse-square law. (d) are special to space travelers.

Light that is polarized along the vertical direction is incident on a sheet of polarizing material. Only 94% of the intensity of the light passes through the sheet and strikes a second sheet of polarizing material. No light passes through the second sheet. What angle does the transmission axis of the second sheet make with the vertical?

Is it possible for one sound wave to cancel another? Explain.

How fast must a bug swim to keep up with the waves it is producing? How fast must a boat move to produce a bow wave?

the ideal efficiency for a heat engine operating between the temperatures 2700 k and 300 k is

A horizontal wire of length 0.53 m, carrying a current of 7.5 A, is placed in a uniform external magnetic field. When the wire is horizontal, it experiences no magnetic force. When the wire is tilted upward at an angle of $19^{\circ}$, it experiences a magnetic force of $4.4 \times 10^{-3} \mathrm{N}$. Determine the magnitude of the external magnetic field.