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View Full Version : Racquet physics/sweetspot question

Gmedlo
05-28-2008, 03:14 PM
If lead tape added to the handle of a racquet lowers the sweetspot because of the added mass, why does putting your hand on the racquet's handle not dramatically lower the sweetspot? (it is much heavier than any lead you add, after all)

There's probably some simple explanation for this, but I can't seem to find anything reasonable...

volleyman
05-28-2008, 05:05 PM
When was the last time you played tennis holding the racquet somewhere other than the handle? :-)

05-28-2008, 05:12 PM
today. I made a bet that i could return this kids serve with the handle... won 20 bucks

volleyman
05-28-2008, 05:23 PM
Did the sweet spot move? If so, where too? :-)

toughshot
05-28-2008, 05:32 PM
Yea, where else would you hold the racket?

They're designed like that..

In other words; just because.

ambro
05-28-2008, 06:04 PM
Because your hand is just the fulcrum. If you put your hand's worth of mass on the handle where your hand usually is, the sweetspot would definitely move a bit, but since your hand is just the point of rotation for the racquet, it is not really involved that much in terms of the sweetspot or mass of the frame.

BullDogTennis
05-28-2008, 06:27 PM
today. I made a bet that i could return this kids serve with the handle... won 20 bucks

play a whole match like that and id be impressed :)

another fun thing to try it to try and play points out by hitting with the beams of the racket...its a toughy

Gmedlo
05-28-2008, 06:44 PM
Because your hand is just the fulcrum. If you put your hand's worth of mass on the handle where your hand usually is, the sweetspot would definitely move a bit, but since your hand is just the point of rotation for the racquet, it is not really involved that much in terms of the sweetspot or mass of the frame.

But what about with players that play with a double-bend forehand without a WW finish, who usually take their wrist out of the equation and use their shoulder as the fulcrum? Wouldn't it make playing virtually impossible?

But, Assuming a player hits with a normal, double bend with WW motion, wouldn't the sweetspot be drastically altered just based on where on the hand the racquet is rotating from? I mean, I've never cut a hand off and weighed it, but I would guess that mine weighs as much as my racquet at least. So, if someone rotates the racquet from the bottom of their palm, their is a significant amount of weight above the fulcrum and now on the lever being used. Would this not lower the sweetspot a sizable amount?

Say none of the above applies; does that then mean that weight added to the handle, under where the hand is, does virtually nothing?

Some of you didn't understand what I was asking, but the point of this thread is to try and get some evidence as to why putting lead in various spots moves the sweetspot. I myself think that the sweetspot doesn't actually move, but the altered swingweight simply results in more energy in the ball, even when hit off of the sweetspot. When I've put lead on the handle, I have never had the sweetspot "move" down on me.

All I've ever heard is "the sweetspot moves towards mass" in relation to adding lead tape. Not once has any evidence been presented. Maybe an experienced MRT/physicist could shed some light on this?

10sfreak
05-28-2008, 06:48 PM
Hmmm...I'm thinking that the sweetspot moves in the direction of the added mass mostly if that mass is added to the hoop. In other words, adding 10 grams to the handle probably won't have nearly the same effect as adding 5 grams to the 6 o'clock position. The weight added to the hoop is more directly linked to where the strings come into contact with the racquet, so that should have more effect. Make sense?

anirut
05-28-2008, 07:05 PM
Here's an experiment if you're willing to try:

Get two rackets of the same model and stung with same string and tension.

One racket you hold firmly with both hands at a set angle face. The other one cast a large concrete block around the handle, setting the angle face same as that held by the hand. (And no, you can't remove it after the test.)

Have a ball machine shoot a ball at the rackets at the same spot on the racket face and measure the distance of the ball bounce.

Let's see if the SP moves.

I don't know if it will move. But the best way is to experiment.