You and a friend are driving to the beach during spring break. you travel 14.5 km east and then 66.5 km south in a total time of 50 minutes. (a) what is the average speed of the trip? (b) what is the magnitude of the average velocity? -in this question for part b, why isnt it necessay to find the unit vectors for displacement?

(a). The average speed is 97.23 km/hr.

(b). The average velocity is 81.70 km/min.

Explanation:

Given that,

Distance in east = 14.5 km

Distance in south = 66.5 km

Time = 50 min = 0.833 hr

(a). We need to calculate the average speed

Using formula of average speed

Where, D = total distance

T = total time

Put the value into the formula

(b). We need to calculate the displacement

Using Pythagorean theorem

Put the value into the formula

(b). We need to calculate the average velocity

Using formula of average velocity

Where, d = displacement

t = time

Put the value into the formula

Here, We can not necessary to find the unit vectors for displacement because we need to the displacement for find the average velocity.

Hence, (a). The average speed is 97.23 km/hr.

(b). The average velocity is 81.70 km/hr.

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.