Biology Forums - Study Force

An ice skater performs a pirouette (a fast spin) by pulling in his outstretched arms close to his body. What happens to his angular momentum about the axis of rotation?
 
  A) It does not change.
  B) It increases.
  C) It changes, but it is impossible to tell which way.
  D) It decreases.

Question 2

The energy required to accelerate a ship the mass of an ocean liner to a cruising speed of 10 of the speed of light is approximately
 
  A) one million times the Earth's current annual energy usage
  B) one hundred times the Earth's current annual energy usage
  C) equal to the Earth's current annual energy usage
  D) ten times the Earth's current annual energy usage

Question 3

The extent of thermal escape in a planetary atmosphere is dependent
 
  A) only on the temperature of its atmosphere
  B) on the temperature and molecular weight of the gases in its atmosphere
  C) only on the thickness of its atmosphere
  D) only on molecular weight of the gases in its atmosphere

Question 4

A terrestrial telescope has focal lengths of 15. mm, 7.5 cm, and 120. cm for eyepiece, erecting lens, and objective respectively.
 
  (a) What is the magnification of the telescope?
  (b) Is this an angular magnification or a lateral size magnification?
  (c) What is its length (objective to eyepiece distance)?

Question 5

A camera uses a biconvex lens made of glass with an index of refraction of 1.60 and has a radius of curvature of 12. cm for the 1st surface and 24. cm for the 2nd.
 
  (a) What is the focal length of this lens when used in air?
  (b) If used under water (n = 1.33), what is the focal length?

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I just wanted to write to say thanks a bunch for the answer!