psd3 034 test one • 06 September 2013 • Name:

1. The left graph is volume versus mass for slabs of soap. The right graph is time versus distance for moving RipStik castor boards.
   
   • For the Soap Density graph:
     1. __________ _____ Calculate the density ρ of the soap.
     2. ______________ Will the soap float or sink?
     3. ______________ Based on the density, what brand of soap is the above bar?
   • For the RipStik Data graph:
     4. _____ Which letter labels the RipStik moving at a constant speed, no acceleration.
     5. _____ Which letter labels the RipStik moving faster at a constant rate of acceleration.
     6. _____ Which letter labels the RipStik moving with a non-constant deceleration .
     7. _______ ___________ Determine the speed of RipStik run C.
     8. _______ ___________ Determine the speed of RipStik run B from 0 to 1 second.
     9. _______ ___________ Determine the speed of RipStik run B from 2 to 5 seconds.
     10. _______ ___________Toughie: Given that for run A distance = ½*acceleration*time² and the coordinate (3 s, 900 cm) shown on the graph, calculate the value of the acceleration. Short form of equation: d=½at²
2. A bar of Lux Magical Spell soap has a length of 7.5 cm, a width of 5.1 cm, a height of 2.0 cm and a mass of 85.0 grams.
   
   1. __________ _____ What is the volume of the soap?
   2. __________ _____ What is the density of the soap?
   3. __________ _____ What will be the slope of the volume versus mass line on an xy scattergraph of volume versus mass for the Lux soap?
3. On Monday I rode a RipStik up a gentle slope, turned around, and came back down the slope.
   
   1. ___________________ What is the name of the shape formed by the curve on the graph?
   2. ___________________ Between zero and seven seconds, what is happening to my velocity?
   3. ___________________ At exactly seven seconds, what is my velocity according to the graph?
   4. ___________________ Between seven and fourteen seconds, what is happening to my velocity?
   5. ___________________Toughie: During the fourteen second run is the direction of the acceleration changing?
4. The data in the table and graphs are from a lab three ball dropping experiment.
   
   _______________ _________ According to the data and graphs, what is the acceleration of gravity?
5. Above and beyond the scope of this course, in the category extremely difficult, given that the curve in problem #3 above has roots (x-intercepts) at (0,0) and (14,0), and a vertex at (7,800), work out the mathematical equation for the curve. This question will not be included in the total possible. Any points awarded will be treated as bonus points.

$\text{slope m}=\frac{(\mathrm{y2}-\mathrm{y1})}{(\mathrm{x2}-\mathrm{x1})}$
Volume V = length l × width w × height h
mass m = density ρ × Volume V
$\rho =\frac{m}{V}$
d = ѵt
$ѵ=\frac{\Delta d}{\Delta t}$
$a=\frac{\Delta ѵ}{\Delta t}$
ѵ = at
d = ½at²
d = ½gt²
where g is the acceleration of gravity.
g = 980 cm/s² (cgs)
g = 9.8 m/s² (mks)