ET372 Final

  1. A golfer estimates that his golfball is  250 yards to the hole.  At the hole, another golfer has dropped a water bottle that is reflecting light back to the golfer and his ball.  What is the approximate time difference based on golfers distance to the hole/water bottle?
  2. A CdS photocell has a resistance versus light intensity as shown in the following graph.  The cell has a time constant of 25 ms.  At t=0, the cell is exposed to a sudden change of light intensity 20 W/m2 to 80 W/m2.  What is the sensor resistance after 20 ms?             Figure 1: CdS Resistance Versus Light Intensity
  3. A force of  120 pounds-force is used to open a valve. What is the are of the diaphragm is a control gauge of 90 kPa (~ 13 psi) must provide this force?
  4. A processing plant is being proposed and will need to use of the city’s water system to be sucessful.  The plant will need a minimum of 2500 gallons of water per minute (gpm) for its operation.  The city’s current water supply pipe to the proposed plant is 12 inches in diameter with a water velocity of 1.5 m/s.  Will the city’s current water supply meet the plant’s needs or will it need to be upgraded?  Show calculations to verify your answer.
  5. From the figure below, construct the truth table for the logic diagram.  What function does this represent?

 

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    1. A golfer estimates that his golfball is 250 yards to the hole.  At the hole, another golfer has dropped a water bottle that is reflecting light back to the golfer and his ball.  What is the approximate time difference based on golfers distance to the hole/water bottle?
    2. A CdS photocell has a resistance versus light intensity as shown in the following graph.  The cell has a time constant of 25 ms.  At t=0, the cell is exposed to a sudden change of light intensity 20 W/m2 to 80 W/m2.  What is the sensor resistance after 20 ms?

Figure 1: CdS Resistance Versus Light Intensity

    1. A force of 120 pounds-force is used to open a valve. What is the are of the diaphragm is a control gauge of 90 kPa (~ 13 psi) must provide this force?
    2. A processing plant is being proposed and will need to use of the city’s water system to be sucessful.  The plant will need a minimum of 2500 gallons of water per minute (gpm) for its operation.  The city’s current water supply pipe to the proposed plant is 12 inches in diameter with a water velocity of 1.5 m/s.  Will the city’s current water supply meet the plant’s needs or will it need to be upgraded?  Show calculations to verify your answer.
    3. From the figure below, construct the truth table for the logic diagram.  What function does this represent?