A 0.32 kg ball is moving horizontally 30. m/s just before bouncing off a wall, thereafter moving 25. ...

A 0.32 kg ball is moving horizontally 30. m/s just before bouncing off a wall, thereafter moving 25. m/s in the opposite direction.
 
  (a) What is the magnitude of its change in momentum?
  (b) What percentage of the kinetic energy was lost in the collision?

Question 2

How might one connect four 10. volt batteries to create one equivalent battery having a potential of 20. volts?
 
  What will be an ideal response?

Question 3

If the intensity of sound changes (increases) by a factor of 100, the decibel level changes by a factor of
 
  A) log 100.
  B) 100.
  C) 20.
  D) 1.
  E) 10.