Four-Bar Linkage and Bouncing Ball Examples

ENGM 373 Dynamics Project

By

Brent Frerichs

In my first problem that I solved analytically, problem 15.257, the answers I received by mathematical calculations that we learned in class were very close to the ones received by using the working model.  As you can see from my work with this problem, the answers received by the working model were very close to the answers I came up with.

VD  = wBDxrD/B + wABxrB/A

= (wk)x(160i) + (1.5k)x(40j)                      so,        VD = 0.066 m/s  at 155o

= 160wBDj – 1.5*40i

-VD cos25 = -1.5*40

VD sin25 = 160wBD

For my second problem I used a ball that would be dropped under gravity from a distance.  Neglecting air resistance, I can find out the speed of the ball just before it hits the ground (Bouncing Ball):

mgh = ½ mv2                              m=1.539 kg

g=9.81 m/s2

h=6.6m

Solving this equation gives v = 11.38 m/s downward.  And as you can see from the graph I have on the model that the velocity just as the ball hits the ground it is approximately 11.5 m/s.