A beam of light in air is incident on the surface of a ...

[Marty]

A beam of light in air is incident on the surface of a rectangular block of clear plastic (n = 1.40). If the speed of the beam before it enters the plastic is 3.00  108 m/s, what is its speed inside the block?
 a. 2.14  108 m/s
  c. 1.94  108 m/s
  b. 2.01  108 m/s
  d. 3.00  108 m/s

Question 2

I take 2.0 kg of ice and dump it into 1.0 kg of water and, when equilibrium is reached, I have 3.0 kg of ice at 0C. The water was originally at 0C. The specific heat of water = 1.00 kcal/kgC, the specific heat of ice = 0.50 kcal/kgC, and the latent heat of fusion of water is 80 kcal/kg. The original temperature of the ice was:
 a. one or two degrees below 0C.
  c. -120C.
  b. -80C.
  d. The whole experiment is impossible.

[chereeb]

Answer to Question 1

A

Answer to Question 2

B

[Marty]

Gracias!

[yeungji]

Excellent