What fan flow rate (in cubic feet per minute, or “cfm”) is required in the ventilation system to turn over the air four times each hour in this room? Each time an automobile tire turns, the tire material flexes and extends in a stress cycle as it takes the weight of the car. How many stress cycles does an average automobile tire go through each year? How high can you be lifted by the energy in a 9v battery?

HOW HIGH CAN A 9V BATTERY LIFT YOU? 9V BATTERY: 1 amp for 30 minutes ==> 9 watts for 0.5 hrs ==> 4.5 watt-hrs Or, estimate how long it could light a 1 watt flashlight bulb Or, data sheet says 5 watt-hrs 4.5 watt-hrs / 746 W/hp x 550 (ft-lb/sec)/hp = 3.3 (ft-lb/sec)-hrs 3.3 x 3600 sec/hrs = ft-lbs For 160 lb person: / 160 = 75 ft!

ESTIMATION PROBLEMS Water flow rate under Washington Av. Bridge Weight of Morrell Hall Gallons of fuel carried by a 747 flying non-stop to Tokyo Average height of trees on U campus Number of people crossing Wash. Av. bridge during class change Load requirements for footbridges in front of Coffman Forces on a bread knife Amount of aluminum (in lbs) in all the pop cans used at the U in a day Pressure under each leg of your chair Velocity of tape in a cassette Energy (all forms) used by the average home in one day Weight of a block of sidewalk concrete Weight of an oil tanker Volume of a ton of bricks Skid distance of a car if brakes applied full while going 60 mph Efficiency of human muscle Peak impact load on the face of a 6 lb. sledge hammer Natural frequency of a downhill ski Time for coffee to cool by 20 deg. Volume of air expelled by professor during a 50 min. lecture

CONVERSIONS 25 Microns =.001 in. 1 mph = 1.47 fps 1 atm = 14.7 psi = 760 mmHg 1 g = 32.2 fss 1 BTU = 778 ft-lbs 1 hp = 550 ft-lbs/s = 746 watts 1 lb = 4.4 Newtons Or, remember equivalent points on scale: 32 deg F = 0 deg C (-40 = -40) 60 mph = 88 fps 1/2 psi = 1 ft of water