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Let Bob have a spaceship with a clock at each end, both of which are synchronized in his frame of reference. Alice has an identical spaceship with a clock at each end, both of which are synchronized in her frame of reference. Her spaceship is docked at the local spaceport, with the front end pointed to the right (positive x direction). Meanwhile, Bob flies by in his ship at a speed V heading to the right (positive x direction). Alice observes Bob’s clocks as he flies by. What does she observe, according to her frame of reference (and lattice of synchronized clocks)? (Tip: Sometimes it helps to draw a picture to visualize what’s going on.)
ByAdmin3. Question 3 Let Bob have a spaceship with a clock at each end, both of which are synchronized in his frame of reference. Alice has an identical spaceship with…
The period of a traveling wave is:
ByAdmin4. Question 4 The period of a traveling wave is: 1 point A measure of how high the wave peaks are. The time it takes for one complete cycle…
Alice creates a machine that can shoot basketballs in a horizontal direction. Using a radar gun, Bob measures the speed of the basketball coming from the machine when it is stationary and finds that it is 30 km/hour. If Alice then puts the machine on top of a car, which she is driving at 10 km/hour away from Bob, and shoots a basketball behind her and toward Bob, what would be the horizontal speed of the ball as Bob measures it, and which direction is it going? (Neglect any effects of air resistance or other sources of friction.)
ByAdmin12. Question 12 Alice creates a machine that can shoot basketballs in a horizontal direction. Using a radar gun, Bob measures the speed of the basketball coming from the machine…
Imagine that Bob, at a spaceport, observes Alice flying by to the right in her spaceship at a velocity of 0.9c. When Alice’s ship had been previously docked at the spaceport, Alice had measured its length as 100 meters. Alice has five clocks on her spaceship: one in front (at 0 meters), one at 25 meters, one at 50 meters, one at 75 meters, and one at the rear at 100 meters. All the clocks are synchronized in Alice’s frame of reference. When Alice flies by Bob, Bob uses his lattice of synchronized clocks to take simultaneous photos of Alice’s clocks (simultaneous in Bob’s frame of reference). Bob compares the times shown in the photos of Alice’s second clock (at 25 meters) and fourth clock (at 75 meters). Which clock is running ahead of the other?
ByAdmin6. Question 6 Imagine that Bob, at a spaceport, observes Alice flying by to the right in her spaceship at a velocity of 0.9c. When Alice’s ship had been previously…
In the “pole in the barn” example done in lecture, even though Alice’s pole is 10 meters long, and Bob’s barn is 8 meters long, Bob thinks that Alice’s pole will fit completely inside as she goes through the barn. Why does he think this?
ByAdmin4. Question 4 In the “pole in the barn” example done in lecture, even though Alice’s pole is 10 meters long, and Bob’s barn is 8 meters long, Bob thinks…
Consider a situation that is similar to that in one of the video lectures, i.e., Alice observing Bob traveling from Earth to a star at a certain distance from Earth. Assume that the Lorentz factor for the relative velocity between Alice’s frame of reference (the Earth-star frame of reference) and Bob’s frame of reference (the spaceship frame of reference) has a value of 4. From Bob’s perspective, he’s at rest and he sees the star rushing toward him. The elapsed time on Bob’s clock between the time Earth passes him and the star passes him is 12 years. How much time does he observe elapse on one of Alice’s clocks?
ByAdmin2. Question 2 Consider a situation that is similar to that in one of the video lectures, i.e., Alice observing Bob traveling from Earth to a star at a certain…