physics CH 35

What is the distance between the earth and the moon for a photon traveling between the 2? Explain.

250,000

What does the formula E=mc2 mean?

A small amount of mass can be converted into a lot of energy (by a multiple of 9*10^16)

A passenger on an interplanetary express bus traveled at 10% the speed of light decides to take a 5 minute catnap by his watch. How long would that catnap last for an observer from a vantage point of one of the 2 planets. How long would the same catnap be from the perspective of the observer if the bus was traveling at 99.99% the speed of light?

If the time of the original is 5 minutes, and c is equal to 1, and v as the percentage of c: which equals 5.025 minutes at 99.99%, which equals 25001 minutes

A twin who makes a long trip at relativistic speed returns younger than his stay at home twin sister. Could he return before his twin sister was born? Defend your answer.

No, time would have to go backwards, which breaks Einstein's equations. (Original time can't be negative, and anything square rooted cannot be negative, therefore relativistic time will never be negative.

At what speeds do relativistic effects occur?

Relativity effects all speeds, but everyday speeds of today (less than even a percent of the speed of light) have relativistic effects that aren't measured.

What evidence do we have that the speed of light is constant in a specific medium?

The Michelson-Morley Experiment measured the speed of light from a star when the earth was rotating both towards and away from it. They discovered that the speed was constant despite the earth's rotation.

Is the mass of a warm cup of tea greater than, less than, or the same as the mass of the same cup of tea when cooled?

The mass of the warm cup of tea is greater because there is greater kinetic energy that must be proportional to the greater mass because of E=mc^2.

Explain what happens to time, mass, momentum, and length at relativistic speeds.

Time slows down, mass increases, momentum increases, length decreases.

Describe some of the everyday consequences that would follow if the speed of light was just 35 mi/hr.

Time would be different for everyone Our masses would fluctuate widely based on every day speed. Length would shorten as people increased their speed. Momentum would fluctuate on everyday speed (increase due to increase in speed)

Explain why the following statement could be a misconception and also why it could be true: "Albert Einstein is the father of the atomic bomb."

True:- He discovered E=mc2, and told Roosevelt by letter to begin the Manhattan Project Misconceived: He didn't help actually build the bomb, and he sent a letter to Truman asking him not to drop the bomb.

Could a person who has a life expectancy of 70 years possibly make a round trip to a part of the universe thousands of light years away?

Yes, due to the theory of relativity, the ship would move close to the speed of light, causing time dilation which would make time on the spacecraft move slower compared to that on Earth. However, earth's age would have passed as many light years as the journey.

Is it possible for a person to be biologically older than one's parents?

Yes, if the parents left at a high percentage of light's speed on a rocket ship or something then time would dilate for the parents and less time would pass for the child because the space/time ratio must be constant to the speed of light