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Re: Golf Ball Trajectory Question

At 02:22 PM 7/15/2003 -0400, you wrote:
...regarding the flight of a struck golf ball. Would
a struck golf ball fly farther on Earth, or in a vacuum (everything
else being equal)?
shouldn't you be able to throw a golf club at least a good percentage
of the distance you can hit the ball

This seemed like an interesting question to me.
...Depending how you parse "throw".
A throwing stick can use the arm swing to accumulate
kinetic energy directly in a projectile (and in the light sling
which constitutes part of a throwing stick) - but I expect
that a hand throw has problems making much speed:
80 mph is probably well within the top percentile
of [baseball] athletic prowess.
Still, I can imagine a throwing stick
providing a greater initial velocity than a hit golf ball.
And from there, I can indeed imagine a club swung fast
in an arc from the hand.

(http://www.wishongolf.com/indepth_traj_bf_software.html)
[says] that a typical amateur golfer with a swing speed of
85 mph would launch the ball with an initial speed of
about 127mph.
The ball would stay aloft for about 5.29 seconds and would
carry 191yards. // with an initial speed of 127 mph, a golf ball
struck in a vacuum should travel farther, because of the lack
of air resistance.

//I assumed an optimum launch angle of 45 degrees.

Here's what I got.

Initial ball speed = (127 miles/hour)(5280 ft./mile)(12 in./ft)
(2.5 cm/in)(1m/100 cm)(1 hr./3600 s) =56.77 m/s

If launched at a 45 degree angle, the vertical component
of velocity will be 28.387 m/s.

*** I make that 56.8 m/s sin(45) = 40.1 m/s

The ball will take 28.387/9.8, or 2.897 seconds to
reach the top of its trajectory and the same amount
of time to return to the ground, so the ball will be
in flight for (2.897)(2) or about 5.79 seconds.

*** I make that t = 2v/a = 80/9.8 = 8.2 sec

Since its horizontal velocity is also 28.387 m/s, the ball
will carry a distance of (28.387 m/s)(5.79 s) or 164.45 m,
which is about 180 yards.

*** I make that x = v.t = 40.1 X 8.2 = 328.8 m

This seems to indicate that the ball struck in the
atmosphere will actually fly farther, the reason being
that it stays aloft for a similar period of time,
but its launch angle is less than 45 degrees, so its
horizontal velocity is greater.

This doesn't "seem right" to me. ///


As others pointed out, one's assumption for the
direction of that initial speed makes quite a
difference to the outcome.



Brian Whatcott Altus OK Eureka!