plz show your work and steps
ty
1) A dog walks at a speed of 1.8m/s along the deck toward the front of a boat that is traveling at 6.6m/s with respect to the water. What is the velocity of the dog with respect to the water? Wat if the dog were walking toward te back of the boat?
2) A vacationer walks 4km/h directly across a cruise ship whose speed relative to the earth is 13.2km/h. What is the speed of the vacationer with respect to the earth?
3)Two trains approach each other on parallel tracks. ach has a speed of 80km/h with respect to the earth. If they are initially 10km apart, how long will it be before they pass each other?
and what does "relative to the Earth" mean?
2007-08-05 10:59:06 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Physics
Speed and velocity need to be measured from a reference.
Since there are typically many reference points available, and since some of them might be moving and since this movement would affect the measurement; it is customary to state the reference point as "with respect to" or "relative to" said reference point or object.
Other than that; velocities obey the simple rules of addition and subtraction when they are so small compared to the speed of light. (Einstein's relativity plays such a small part that it can be ignored.)
The only complexities are in questions 2 & 3.
For question 2; it is because one has to draw a two dimensional diagram to visualize the motions involved.
You will get a right angled triangle with the answer being the longest side of the triangle (the hypotenuse).
You can use the Pythagorean theorem to calculate this hypotenuse eg.
Speed (with respect to Earth) =
squareroot(13.2 ^2 + 4^2)
(Where the " ^2 " symbol denotes squaring.)
For question 3; you will need to define exactly what you mean by "passing:" one another and what points are used when making the 10 km measurement. Are they the locomotives or the cabooses or the middles of the trains? One can make assumptions but that is all that they would be.
As worded; my first assumption would be that I would be expected to treat the trains as points.
I would also be forced to assume that the distance between the tracks was negligable.
Other than that it is simple arithmetic the doing of which might insult most people.
2007-08-05 16:29:05 · answer #1 · answered by J C 5 · 0⤊ 0⤋
Relativity questions?
2007-08-05 11:02:01 · answer #2 · answered by Anonymous · 1⤊ 0⤋
relative to the earth means relative to the ground
2007-08-05 11:15:31 · answer #3 · answered by Tom B 2 · 0⤊ 0⤋