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  Topic Review (Newest First)
02-02-2013 02:08 AM
Marian
Re: Racket head speed of pros vs recs?

That's in light with this youtoube:
http://www.youtube.com/watch?v=OaZtx...QZFTvtJUheX4LQ
02-02-2013 01:17 AM
Marian
Re: Racket head speed of pros vs recs?

Hi,

http://www.tennis.com/gear/2013/01/c.../#.UQwqtx1bNes

Law of Conservation of Momentum:
What that means is that the two momentum (of the racket and the ball, after the impact) have to be equal and with a heavier racket, the ball's speed will be increased, while the racket will not slow down as much (being more stable in your hands, as opposed to lighter frames).

Now that got me thinking? Which one of the two would be affected more?
The crux of the problem being:

1. Would we be hitting much harder with a heavier racket?
or
2. Would the heavier racket be drastically more stable?

What's your guess?

So, I've dusted off my rusty physics (ahem, googled it: http://en.wikipedia.org/wiki/Elastic_collision) and the answer is:

I’ve done some calculations (based on the equations bellow) and it seems that by adding 100g to a 500g racket:

2. We’d be hitting about 18% harder and the heavier racket(by 100g) would be about 13% more stable.

A bit more realistic calculations, with the ball at around 60g and considering that the pros hit in average around 75-85 mph and the hardest at around 100 mph, so they probably are able to swing the racket faster, say at 10 m/s:

Example A:
Ball: mass = 0.06 kg , velocity = 30 m/s (around 60 mph)
Racket: mass = 0.5 kg, velocity = -10 m/s

After collision:
Ball: velocity = -41.4 m/s (about 93 mph)
Racket: velocity = - 1.42 m/s (The racket continues to swing forward at around 14% of the original speed)
--------------------------------------------------------------
Example B:
Ball: mass = 0.06 kg , velocity = 30 m/s (around 60 mph)
Racket: mass = 0.6 kg, velocity = -10 m/s

After collision:
Ball: velocity = -50 m/s (around 100 mph an increase of 18% when hitting with the heavier racket)
Racket: velocity = -2.7 m/s (The heavier racket continues to swing forward at around 27% of the original speed. Hence more stable, less impact on the arm and inducing longer swings/easier to go more through the ball as opposed to coming over too soon)

A comparison with (60g balls in both cases), seems to give (for a 1 m/s swing aka drop shot):

Example A:
Ball: mass = 0.06 kg , velocity = 30 m/s
Racket: mass = 0.5 kg, velocity = -1 m/s

After collision:
Ball: velocity = -25.35 m/s (you are hitting slower then the incoming ball)
Racket: velocity =5.6 m/s (your arm is pushed back)
--------------------------------------------------------------
Example B:
Ball: mass = 0.06 kg , velocity = 30 m/s
Racket: mass = 0.6 kg, velocity = -1 m/s

After collision:
Ball: velocity = -26.36 m/s (you are hitting just 4% faster)
Racket: velocity = 4.6 m/s (your raquet is 22% more stable)

That means that at slow swings (aka drop shots), one just gets stability out of heavier raquets…No surprise there

Equations
One-dimensional Newtonian


Let m1 and m2 be the masses, u1 and u2 the velocities before collision, and v1and v2 the velocities after collision.
The conservation of the total momentum demands that the total momentum before the collision is the same as the total momentum after the collision, and is expressed by the equation

m1u1 +m2u2 = m1v1+m2v2

Likewise, the conservation of the total kinetic energy is expressed by the equation

m1u1u1/2 +m2u2u2/2= m1v1v1/2+m2v2v2/2

NOTE: The collision is probably not totally elastic, but rather around 85% (according to USTA), so this science is simplified....

These equations may be solved directly to find vi when ui are known or vice versa. However, the algebra involved can be cumbersome[dubious – discuss]. An alternative solution is to first change the frame of reference such that one of the known velocities is zero. The unknown velocities in the new frame of reference can then be determined and followed by a conversion back to the original frame of reference to reach the same result. Once one of the unknown velocities is determined, the other can be found by symmetry.
Solving these simultaneous equations for vi we get:

v1= (u1(m1-m2)+2m2u2)/(m1+m2)

v2=(u2(m2-m1)+2m1u1)/(m1+m2)


HTH,
Fintft@yahoo.com
10-25-2012 09:25 PM
MaxPower
Re: Racket head speed of pros vs recs?

djez don't overestimate tennis players. The difference lies in the control, not in the actual speed or power. They are only human.

The actual challenge was HITTING A RACKET INTO A CONCRETE WALL? Not even hit a ball into a wall?

Not much technique swinging a racket into a concrete wall....one thing if you said serving or something but even at my local club rec players can serve 160-180km/h and it's not like Nadal is breaking the soundbarrier with his serves.

I'd personally take on Nadal in a "swing the racket into a concrete wall" challenge. If he even reached 1,5x my result I'd be very impressed. Most likely the difference would be 20-30% if that.
10-25-2012 09:19 PM
Haelfix
Re: Racket head speed of pros vs recs?

The energy transfer is certainly not a linear relation, and the efficiency is much greater for a pro b/c they hit the ball perfectly with perfect strings etc. I'd say they can probably generate rh speed on the order of 15% greater? Something like that.
10-25-2012 09:04 PM
Agrajag
Re: Racket head speed of pros vs recs?

Quote:
Originally Posted by out_grinder View Post
I thought the big difference is that even if you swing it as hard as you physically can (regardless of whether you hit the ball or not), the actual racket is only traveling about 5% of the speed of the pro's racket.
If that was the case, they would be able to hit their forehands at least 10 times faster. The energy conversion efficiency is probably substantially worse when you swing the racket that much faster, but still.

Pros can hit forehands about 180km/h, that would mean you can only hit yours at 18km/h.
10-25-2012 08:52 PM
out_grinder
Re: Racket head speed of pros vs recs?

Quote:
Originally Posted by Agrajag View Post
My guesstimate is probably 10-30%. The big difference is that they are able to hit the ball cleanly every single time. I am not.
I thought the big difference is that even if you swing it as hard as you physically can (regardless of whether you hit the ball or not), the actual racket is only traveling about 5% of the speed of the pro's racket.
10-25-2012 08:47 PM
Agrajag
Re: Racket head speed of pros vs recs?

Quote:
Originally Posted by out_grinder View Post
By racket head speed I'm talking literal racket head speed. Not in relation to hitting a ball. Just how fast you can physically swing a racket.

Say you swing a racket into a concrete wall and the concrete wall can somehow detect how much force you supplied on decimating the racket. You're a rec tennis player but a rec tennis player with a history in elite strength training. You threw javelin for your country. And you're up against Nadal.

My guess is that Nadal is going to hit the concrete wall about 5 - 10x harder than you with his racket.

What do you think?
My guesstimate is probably 10-30%. The big difference is that they are able to hit the ball cleanly every single time. I am not.
10-25-2012 08:42 PM
Haelfix
Re: Racket head speed of pros vs recs?

Quote:
Originally Posted by out_grinder View Post
By racket head speed I'm talking literal racket head speed. Not in relation to hitting a ball. Just how fast you can physically swing a racket.

Say you swing a racket into a concrete wall and the concrete wall can somehow detect how much force you supplied on decimating the racket. You're a rec tennis player but a rec tennis player with a history in elite strength training. You threw javelin for your country. And you're up against Nadal.

My guess is that Nadal is going to hit the concrete wall about 5 - 10x harder than you with his racket.

What do you think?
First of all, almost no pro hits the ball as hard as they can. They don't swing out of control and neither does a rec player.

Depending on the rec player you see guys hit 100-115 mph serves. Contrast that with the upper tier pros, which is 150 mph or so. So roughly a 50% increase in pace. I'd say thats about the difference in fhs or bhs as well. If a guy hits at 60mph, a pro will hit the same ball at 90mph.
10-25-2012 08:42 PM
Uncle Latso
Re: Racket head speed of pros vs recs?

Quote:
Originally Posted by out_grinder View Post
By racket head speed I'm talking literal racket head speed. Not in relation to hitting a ball. Just how fast you can physically swing a racket.

Say you swing a racket into a concrete wall and the concrete wall can somehow detect how much force you supplied on decimating the racket. You're a rec tennis player but a rec tennis player with a history in elite strength training. You threw javelin for your country. And you're up against Nadal.

My guess is that Nadal is going to hit the concrete wall about 5 - 10x harder than you with his racket.

What do you think?
Possibly a bit harder, perhaps not 10x.

It's much more distinctive at serve, as it takes much, much more technique to produce a powerful shot, compared to FH.
10-25-2012 08:33 PM
out_grinder
Racket head speed of pros vs recs?

By racket head speed I'm talking literal racket head speed. Not in relation to hitting a ball. Just how fast you can physically swing a racket.

Say you swing a racket into a concrete wall and the concrete wall can somehow detect how much force you supplied on decimating the racket. You're a rec tennis player but a rec tennis player with a history in elite strength training. You threw javelin for your country. And you're up against Nadal.

My guess is that Nadal is going to hit the concrete wall about 5 - 10x harder than you with his racket.

What do you think?

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