Phy 120 Prelab 2

Combining Errors

Before you come to the laboratory, test yourself on your understanding of combining experimental errors by imagining that a quantity Q is computed from measured values of x and y according to

Q = 10 x/y2.

The values obtained experimentally are (to 90% confidence)

x = 5.00 +/- 0.01

y = 15.00 +/- 0.03.

Questions:

  1. How much is Q uncertain due to the uncertainty of x?

  2. How much is Q uncertain due to the uncertainty of y?

  3. What is the value of Q, to 90% confidence?  Be sure to show the uncertainties combine to obtain the net uncertainty in Q?