A sailboat tacking against the wind moves as follows: 4.7 km at 37o east of north, 4.4 km at 25o west of north, and 2.2 km at 36o east of north. The entire trip takes 1 h and 40 min. What is the displacement of the sailboat at the end of the trip? What is the magnitude of the average velocity of the sailboat for this trip?

What is the magnitude of the average instantaneous speed of the sailboat for this trip?

At what angle would the boat have sailed to reach its destination directly? Assume north is 0o and east is 90o.

explanation:

v=uf/(u-f)

= 5.-10/(5+10) convex lens has negative focal length

where are the vectors ?

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.