A ball can be hit faster if it is projected without spin, but it can be hit farther if it is projected with backspin. Measurements of the tradeoff between the speed and spin for a baseball impacting a baseball bat are presented. The results are inconsistent with a collision model in which the ball rolls off the bat and instead imply tangential compliance in the ball, the bat, or both. If the results are extrapolated to the higher speeds that are typical of the game of baseball, they suggest that a curveball can be hit with greater backspin than a fastball, but by an amount that is less than would be the case in the absence of tangential compliance.

1.
G. S.
Sawicki
,
M.
Hubbard
, and
W. J.
Stronge
, “
How to hit home runs: Optimum baseball swing parameters for maximum range trajectories
,”
Am. J. Phys.
71
,
1152
1162
(
2003
).
2.
R. K.
Adair
, “
Comment on ‘How to hit home runs
,’
Am. J. Phys.
73
,
184
185
(
2005
);
G. S.
Sawicki
,
M.
Hubbard
, and
W. J.
Stronge
, “
Reply to ‘Comment
,’
Am. J. Phys.
73
,
185
189
(
2005
).
3.
R.
Cross
, “
Measurements of the horizontal coefficient of restitution for a superball and a tennis ball
,”
Am. J. Phys.
70
,
482
489
(
2002
).
4.
R.
Cross
, “
Grip-slip behavior of a bouncing ball
,”
Am. J. Phys.
70
,
1093
1102
(
2002
).
5.
R.
Cross
, “
Measurements of the horizontal and vertical speeds of tennis courts
,”
Sports Eng.
6
,
95
111
(
2003
).
6.
R.
Cross
, “
Oblique impact of a tennis ball on the strings of a tennis racquet
,”
Sports Eng.
6
,
235
254
(
2003
).
7.
R.
Cross
, “
Bounce of a spinning ball near normal incidence
,”
Am. J. Phys.
73
,
914
920
(
2005
).
8.
R.
Cross
, “
The coefficient of restitution for collisions of happy ball, unhappy balls, and tennis balls
,”
Am. J. Phys.
68
,
1025
1031
(
2000
).
9.
R.
Cross
, “
Impact of a ball with a bat or racket
,”
Am. J. Phys.
67
,
692
702
(
1999
).
10.
A. M.
Nathan
, “
Dynamics of the baseball-bat collision
,”
Am. J. Phys.
68
,
979
990
(
2000
).
11.
H.
Brody
, “
The moment of inertia of a tennis ball
,”
Phys. Teach.
43
,
503
505
(
2005
).
12.
The value of the normal coefficient of restitution depended somewhat on the relative normal ball-bat velocity and was approximately 0.435 for the fastball and 0.450 for the curveball.
13.
H.
Brody
, “
That’s how the ball bounces
,”
Phys. Teach.
22
,
494
497
(
1984
).
14.
N.
Maw
,
J. R.
Barber
, and
J. N.
Fawcett
, “
The oblique impact of elastic spheres
,”
Wear
38
,
101
114
(
1976
).
15.
N.
Maw
,
J. R.
Barber
, and
J. N.
Fawcett
, “
The role of elastic tangential compliance in oblique impact
,”
J. Lubr. Technol.
103
,
74
80
(
1981
).
16.
R.
Garwin
, “
Kinematics of an ultraelastic rough ball
,”
Am. J. Phys.
37
,
88
92
(
1969
).
17.
W.
Stronge
,
Impact Mechanics
(
Cambridge U.P.
, Cambridge, UK,
2000
).
18.
A. M.
Nathan
, “
Characterizing the performance of baseball bats
,”
Am. J. Phys.
71
,
134
143
(
2003
).
19.
H.
Brody
,
R.
Cross
, and
C.
Lindsey
,
The Physics and Technology of Tennis
(
Racquet Tech
, Solana Beach, CA,
2002
).
20.
R. G.
Watts
and
S.
Baroni
, “
Baseball-bat collisions and the resulting trajectories of spinning balls
,”
Am. J. Phys.
57
,
40
45
(
1989
).
AAPT members receive access to the American Journal of Physics and The Physics Teacher as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.