__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.

V_{D }= w_{BD}xr_{D}_{/B
}+ w_{AB}xr_{B}_{/A}

= (wk)x(160i) +
(1.5k)x(40j)
so, V_{D }= 0.066
m/s at 155^{o}

= 160w_{BD}j – 1.5*40i

-V_{D }cos25 = -1.5*40

V_{D }sin25 = 160w_{BD}

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 mv^{2 } m=1.539 kg

g=9.81 m/s^{2}

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.