1 - A swimmer wants to swim straight across a river with current flowing at a speed of v1 = 0.27 km/h. If the swimmer swims in still water with speed v2 = 0.81 km/h, at what angle should the swimmer point upstream from the shore and at what speed v will the swimmer swim across the river?

2 - In the 1887 experiment by Michelson and Morley, the length of each arm was 11 m. The experimental limit for the fringe shift was 0.005 fringes. If sodium light was used with the interferometer ( = 589 nm), what upper limit did the null experiment place on the speed of the Earth through the expected ether?

3 - Astronomers discover a planet orbiting around a star similar to our sun that is 15 light years away. How fast must a rocket ship go if the round trip is to take no longer than 30 years in time for the astronauts aboard?
How long will the trip take as measured on Earth?

4 - A spaceship is moving at a speed ot 0.7c away from an observer at rest. A boy in the spaceship shoots a proton gun with protons having a speed of 0.8c.
(a) What is the speed of the protons measured by the observer at rest when the gun is shot away from the observer?
(b) What is the speed of the protons measured by the observer at rest when the gun is shot toward the observer?

Hi, I need assistance answering the following question:
An athlete swings a 2.26 kg ball horizontally on the end of a rope. The ball moves in a circle of radius 0.59 m at an angular speed of 0.56 rev/s. What is the tangential speed of the ball? Answer in units of m/s.

Flying against the jetstream, a jet travels 1890km in 3 hours. Flying with the jetstream, the same jet travels 4650km in 5 hours. What is the speed of the jet in still air, and what is the speed of the jetstream?

Flying against the jetstream, a jet travels 2600km in 4 hours. Flying with the jetstream, the same jet travels 6060km in 6 hours. What is the speed of the jet in still air, and what is the speed of the jetstream?

Two protons are released from the res when they are 0.8nm apart.
1. What is the maximum speed they will reach?
2. When does this speed occur?
3. What is the maximum acceleration they will achieve?
4. When does this acceleration occur?

Driving along a crowded freeway, you notice that it takes a time t to go from one mile marker to the next. When you increase your speed by 4.0 mi/h, the time to go one mile decreases by 12 s. What was your original speed?
....... mi/h ?

A child in an airport is able to cover 392 meters in 4 minutes running at a steady speed down a moving sidewalk in the direction of the sidewalk's motion. Running at the same speed in the direction opposite to the sidewalk's movement, the child is able to cover 350 meters in 5 minutes. What is the child's running speed on a stil

Question: The index of refraction of a diamond is 2.42. This means that a given wavelength of light travels
a. 2.42 times faster in the diamond than it does in the vacuum
b. 2.42 times faster in the diamond than it does in the air
c. 2.42 times faster in the vacuum than it does in the diamond
d. 2.42 times faster in the ai

1:The outside of a frame measures 14 in by 20 in. 224 in^2 of the picture shows. Find the thickness of the frame?
2:The outside of a frame measures 11 in by 12 in. 30 in^2 of the picture shows. Find the thickness of the frame?
3: A car travels 910 mi at a certain speed. if the speed had been 5 miles per hour faster, the tr