A runner generates 1260 W of thermal energy. If this energy has ...

[theo]

A runner generates 1260 W of thermal energy. If this energy has to be removed only by evaporation, how much water does this runner lose in 15 minutes of running? The latent heat of vaporization of water is 22.6  105 J/kg.
 
  A) 50 g
  B) 500 g
  C) 35 g
  D) 350 g
  E) 40 g

Question 2

A geologist suspends a 0.30-kg stone on an ideal spring. In equilibrium the stone stretches the spring 2.0 cm downward.
 
  The stone is then pulled an additional distance of 1.0 cm down and released from rest.
  (a) Write down the equation for the vertical position y of the stone as a function of time t, using the cosine function. Take the origin at the equilibrium point of the stone, with the positive y direction upward.
  (b) How fast is the stone moving at a time equal to 1/3 of its period of motion?

[tuwy]

Answer to Question 1

B

Answer to Question 2

(a) y = -(0.010 m) cos(22 s-1 t) (b) 0.19 m/s

[theo]

Gracias!

[juliaf]

Wow, this really help