Directions for Bat Chooser & Reaction Time Activities

Directions for Bat Chooser & Reaction time activities: Reaction time: Tester - stand on chair & hold yardstick at the 36” end. Testee- position finger & thumb opposed to the 0” end. Focus on the end of the stick between the finger & thumb. When released by tester you will see the end of the stick begin to fall, squeeze & hold the stick. Record the ∆y (in inches). Do a practice trial & 3 recorded trials. Calculate your reaction time as the average of the 3 trials.

An ave reaction time <.17s is “quick”, .17-.23s = ave., >.23s is “nonquick” when considering the slope to use for BBS pg 115 Bat Chooser (although you are not being asked to do this extension).

A data table & calculation will be part of tonight’s homework

∆y = .5gt2 g = 32 ft/s (convert between inches & feet to calculate reaction time)

Bat Chooser Swing as fast as possible while maintaining control (hold) of the bat. Stretch a little before beginning. Each person will do 3 trials. Rotation of tester will take place after each trial ( a set of 5 swings). A = tube/sponge bat B = composite (Resin & fiber) C = Aluminum D = Wood E = Mandril /fiber/polyester

Sequence of test swings; Trial 1 A, B, C, D, E

Trial 2 E, D, C, B, A

Trial 3 C, D, B, E, A

I will aim the swing speed detector at the center of mass. Kinetic energy is to be calculated. A graph with a line of best fit for swing speed vs weight & KE vs weight is to be constructed (like the one on pg 103 of the Bat Chooser (Watts & Bahill; 1990). KE=.5mv2 m= (kg), v= (m/s). KE scale is calibrated so that KE max = .55 length of y- axis. The left & right y-axis are of the same length with left axis calibration determined by swing speed range We will consider the intersection point of these two slopes to be the point of interest.

A team member will record the raw data for you; you will record the data for a teammate. So the complete homework assignment is to calculate Reaction Time (ave.) & kinetic energy of each swing (using the ave. velocity value for each bat), and to plot the line of best fit for the swing speed & KE, as previously described.