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MACHINE DESIGN  An
3141
PROBLEM 314
Statement:
Figure P35 shows a child's toy called a pogo stick.
The child stands on the pads, applying
half her weight on each side.
She jumps off the ground, holding the pads up against her feet, and bounces
along with the spring cushioning the impact and storing energy to help each rebound. Find the natural
frequency of the system, the static deflection of the spring with the child standing still, and the dynamic force
and deflection when the child lands after jumping 2 in off the ground.
P
F /2
i
F /2
i
Units:
blob
lbf sec
2
.
in
Given:
Child's weight
W
c
60
lbf
.
Spring constant
k
100
lbf
.
in
1
.
Pogo stick weight
W
p
5
lbf
.
Height of drop
h
2
in
.
Assumptions:
1. An approximate energy method will be acceptable.
2. The correction factor for energy dissipation will be applied.
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This note was uploaded on 04/26/2010 for the course MAE 3242 taught by Professor N/a during the Spring '10 term at University of TexasTyler.
 Spring '10
 N/A
 Machine Design

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