Laboratory
10 The Sweet Spot | MECH324 Dynamics
of Machines |
| Name:
__________________________ | Lab Sect. _______ |
Date: _______________ |
SHOW
WORK WHERE SPACE IS GIVEN
EXPERIMENTAL
- Mass
of bat, m: ________(kg) (it should be 0.84 kg, unless a different
bat is used)
- Distance from origin to center of rotation, COR:
________(m)
- Length of bat, Lbat: ________(m)
- Distance from origin to center of gravity, CG: ________(m)
- Length of string 1, L1 (if applicable): ________(m)
- Length of string 2, L2 (if applicable): ________(m)
- Distance from pivot point to CG, LCG: ________(m)
- Distance from pivot point to center of rotation, LCOR:
________(m)
- Natural frequency of swinging bat in Hz, fo:
________(Hz)
- Natural frequency of swinging bat in rad/sec,
Ωo: ________(rad/sec)
- Moment
of inertia about the pendulum's pivot point, Io:
Io=__________(kg*m2)
- Moment of inertia about the bat's center of gravity, ICG.
ICG=__________(kg*m2)
- Moment of inertia about the bat's center of rotation, ICOR.
ICOR=__________(kg*m2)
- Radius of gyration, k.
k=__________(m)
- Distance from the CG to the center of percussion, lp.
lp=_________(m)
- Distance from the
handle to the sweet spot.
sweet spot=_________(m)
THEORETICAL
Draw
a model of the bat, TO SCALE, using AT LEAST 3 simple geometrical volumes.
Label:
- names of volumes (e.g., cylinder, conical frustum) with labels (e.g.,
"A", "B", etc)
- draw "negative" volumes as
dotted lines
- dimensions of shapes (e.g., lengths, widths, radii)
- put
a "+" at each center of gravity for individual shapes (use table
to determine CGs)
- distances to each CG from origin
- Distance from origin to center of gravity, CG.
CG: ________(m)
- Label the CG (of the whole bat)
on your model with a star.
- In the table below, list the
moments of inertia for each volume in your model
| VOLUME LABELS | Moment
of Inertia, IGG | Mass,
m | Distance from Origin, d | Moment
of Inertia about Origin (IGG +
md2) |
| | | | |
| | | | |
| | | | |
| | | | |
| | | | |
| | | | |
| | | | |
| | | | |
- Moment of inertia about the bat's origin, IZZ.
IZZ=__________(kg*m2)
- Moment of inertia about the bat's center of gravity, ICG.
ICG=__________(kg*m2)
- Moment of inertia about the bat's center of rotation, ICOR.
ICOR=__________(kg*m2)
- Radius of gyration, k.
k=__________(m)
- Distance from the CG to the center of percussion, lp.
lp=_________(m)
- Distance from the
handle to the sweet spot.
sweet spot=_________(m)
THE
"REAL SWEET SPOT"
- Distance from the handle to the sweet
spot.
sweet spot=_________(m)
- Error of
experimental sweet spot: _________(%)
- Error of theoretical
sweet spot: _________(%)