The Naked Scientists

The Naked Scientists Forum

Author Topic: Balls keeping low  (Read 7544 times)

Offline DERRINALPHIL

  • First timers
  • *
  • Posts: 9
    • View Profile
Balls keeping low
« on: 27/03/2007 12:41:42 »
Dear Naked Scientists,

I am a cricket umpire in Australia and I have always been interested by balls "keeping low".

Batsmen confronted by a "grubber" are always late on their shot. The delivery seems to be past them before they have time to react.

Obviously the ball loses little kinetic energy to potential energy as it stays low. I have read somewhere that a delivery slows markedly when it hits the ground. Here are the two ways that a delivery speed may vary once it leaves the bowlers hand.

I reckon that the impact of the ball on the ground would be the major influence. If it hit a slightly angled bit of turf it could skid rather than bounce.

What do you think?

Phil


 

Offline daveshorts

  • Moderator
  • Neilep Level Member
  • *****
  • Posts: 2583
  • Physics, Experiments
    • View Profile
    • http://www.chaosscience.org.uk
Balls keeping low
« Reply #1 on: 27/03/2007 12:59:45 »
There are a few things that could have this effect that I can think of, I don't know what the bowler is doing to achieve it so I am not sure which if any it would be:

If the ball isn't spinning and hits the ground and grips it will be once it leaves the ground this will slow it down considerably as energy and momentum have to be transferred to the spinand therefore make it rise more vertically


So if it slips rather than grips it will bounce lower and leave the ground faster



If the bowler could apply topspin to the ball this would have a similar effect, but in a more predictable way

I don't know if that helps
 

Offline daveshorts

  • Moderator
  • Neilep Level Member
  • *****
  • Posts: 2583
  • Physics, Experiments
    • View Profile
    • http://www.chaosscience.org.uk
Balls keeping low
« Reply #2 on: 27/03/2007 13:01:03 »
Hitting an angled piece of turf would also help
 

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • Posts: 12656
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
Balls keeping low
« Reply #3 on: 27/03/2007 13:16:26 »
A real "grubber" doesn't just keep low, it more-or-less stays at ground level (or even rolls along the ground) after bouncing. It is caused by the ball hitting uneven or spongy ground. Shane Warne's famous "flipper" has heavy top spin which causes the ball to accelerate when it bounces. Imparting back spin will cause the ball to slow. However, in both instances the ball will bounce to roughly the expected height.

As far as the batsman not having time to play the shot, there is a reason for that. It is not until the ball is below eye-level that the batsman can predict where it will bounce (that is why very tall bowlers such as Joel Garner & Vincent Van Der Bijle caused such problems). So, as soon as the ball is below that level, the batsman will get his bat into the position he expects the ball to be when it reaches him. If the ball stays much lower, or bounces much higher, there is not time for him to re-adjust. So even a spin or medium pace bowler will cause major problems if the ball grubs.
« Last Edit: 27/03/2007 13:21:49 by DoctorBeaver »
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Balls keeping low
« Reply #4 on: 28/03/2007 04:44:57 »
I understand they tend to hang lower with age and this probably correlates with less physical energy. Or is this the wrong thread I am in?
 

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • Posts: 12656
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
Balls keeping low
« Reply #5 on: 28/03/2007 08:10:41 »
I understand they tend to hang lower with age and this probably correlates with less physical energy. Or is this the wrong thread I am in?

Well I'm getting old and I have less physical energy - but I can't say I've noticed that they're hanging lower  [:I]
 

Offline science_guy

  • Hero Member
  • *****
  • Posts: 701
  • I'm right there... inside neilep's head!
    • View Profile
Balls keeping low
« Reply #6 on: 28/03/2007 16:19:48 »
wait a minute...

when you say "bowler" do you mean the guy on the mound who throws the ball at the guy with the bat, who then hits it?

where I come from, they call that a "pitcher". ;)
 

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • Posts: 12656
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
Balls keeping low
« Reply #7 on: 28/03/2007 18:24:54 »
Bowlers do not just stand on a little bump & throw balls at people. They run up to the wicket do deliver the ball at up to 100mph.
 

paul.fr

  • Guest
Balls keeping low
« Reply #8 on: 28/03/2007 18:51:32 »
wait a minute...

when you say "bowler" do you mean the guy on the mound who throws the ball at the guy with the bat, who then hits it?

where I come from, they call that a "pitcher". ;)

You are talking about that mind numbingley boring game of Baseball, where americans play other americans in the "world series"!!!


Bowlers do not just stand on a little bump & throw balls at people. They run up to the wicket do deliver the ball at up to 100mph.

run speed plus bowling speed, yes?
 

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • Posts: 12656
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
Balls keeping low
« Reply #9 on: 29/03/2007 13:32:34 »
Well I don't know many people who can run at 100mph!  [|)]
 

Offline science_guy

  • Hero Member
  • *****
  • Posts: 701
  • I'm right there... inside neilep's head!
    • View Profile
Balls keeping low
« Reply #10 on: 29/03/2007 15:58:02 »
soooo... what is cricket? can anyone explain it to the clueless American?
 

Offline ukmicky

  • Moderator
  • Neilep Level Member
  • *****
  • Posts: 3011
    • View Profile
    • http://www.space-talk.com/
Balls keeping low
« Reply #11 on: 29/03/2007 16:31:09 »
Its like baseball but with cricket you run backwards and forwards between two wickets instead of round and round in circles. Also  the cricket ball  hits the ground before its attacked by the batsman allowing  spin placed on the ball which causes it change direction when it hits the ground more so than when a ball is pitched just through the air as in baseball.


Cricket used to be played in the US due to english immigrants i believe and probably still is in places. but these days you prefer to play baseball which started off as rounders which is basically British childrens game.

 

Offline science_guy

  • Hero Member
  • *****
  • Posts: 701
  • I'm right there... inside neilep's head!
    • View Profile
Balls keeping low
« Reply #12 on: 29/03/2007 16:34:19 »
I ask you this though... dont all games start out as childrens games?
 

paul.fr

  • Guest
Balls keeping low
« Reply #13 on: 29/03/2007 17:57:19 »
soooo... what is cricket? can anyone explain it to the clueless American?

it's that boring game that we english tend to lose at.  :)
 

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • Posts: 12656
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
Balls keeping low
« Reply #14 on: 30/03/2007 08:43:44 »
 

Offline DERRINALPHIL

  • First timers
  • *
  • Posts: 9
    • View Profile
Balls keeping low
« Reply #15 on: 30/03/2007 09:49:57 »
Dear Scienceguy,

Cricket is a game played and loved by people who speak English. The two go hand in hand. The Poms gave two great gifts to the world: the English language and Cricket.

This is why cricket has never caught on in the USA.

Do not try to understand the game.

Phil
 

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • Posts: 12656
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
Balls keeping low
« Reply #16 on: 30/03/2007 13:45:44 »
Cricket is a game played and loved by people who speak English.

That's why David Beckham plays football  :D
 

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • Posts: 12656
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
Balls keeping low
« Reply #17 on: 30/03/2007 13:49:33 »
Science_Guy

It's very simple:-

You have 2 sides, one out in the field and one in. Each man that's in the side that's in goes out until he's out and when he's out he comes in and the next man goes in until he's out.
When they are all out, the side that's out goes in, and the side that's been in goes out and tries to get those coming in out. Sometimes you get men still in and not out. When both sides have been in and out, including the not outs (who are still in unless all the others are out), that's the end of the game; unless it's a 1st class game in which case they go in and out twice each. (Although sometimes the team in 1st stays out until the side that were out, but then in, are out twice.)
« Last Edit: 30/03/2007 13:54:34 by DoctorBeaver »
 

Offline science_guy

  • Hero Member
  • *****
  • Posts: 701
  • I'm right there... inside neilep's head!
    • View Profile
Balls keeping low
« Reply #18 on: 30/03/2007 15:43:03 »
so, from what you tell me so far, It is still kind of like baseball in the ins and outs (yes, I was able to sort that out  :P)

But, can you explain the scoring system and how you get a person "out"?
 

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • Posts: 12656
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
Balls keeping low
« Reply #19 on: 31/03/2007 12:09:44 »
Each time a batsman runs from 1 wicket to the other, that's a run. But both batsmen have to run to the opposite wicket for it to count. If the batsman hits the ball and it crosses the boundary rope without touching the ground 1st, that's 6 runs. If it touches the ground 1st that's 4 runs.

Then there are "extras". If the bowler's front foot is over the front crease when he delivers the ball, that's called a "no ball". If the ball is delivered so that it's too far away for the batsman to hit, that's a wide (not strictly true but close enough). If the batsman fails to hit the ball but they still get a run, that's a bye. If it hits the batsman's leg and they get a run, that's a leg bye. A no ball and a wide count as 1 run to the batting team and for byes & leg byes it depends how many times they run between the wickets.

A batsman can be out in several ways:-
Bowled - the ball is bowled and knocks the bails off of his wicket (the bails being the 2 smaller pieces of wood that lay across the top of the 3 upright stumps).
Caught - the batsman hits the ball and it is caught before touching the ground.
LBW (Leg Before Wicket) - the ball hits the batsman's leg without hitting the bat and the umpire judges it would have gone on to hit the wicket.
Run out - the batsman runs but the ball is thrown at the wicket & dislodges the bails before he has made his ground.
Stumped - the wicketkeeper takes the ball and uses it to dislodge the bails while the batsman is out of his ground.
Timed out - a player stays in the bar too long when he should be going out to bat (this was the most common cause of my own frequent dismissals).
I suppose now you want to know the difference between a googlie & a chinaman.

« Last Edit: 31/03/2007 12:14:03 by DoctorBeaver »
 

paul.fr

  • Guest
Balls keeping low
« Reply #20 on: 31/03/2007 12:11:56 »
Doc B,

one thing i never understand about cricket, how can one team be so far in the lead yet it end up a draw! how does that work?
 

Offline DERRINALPHIL

  • First timers
  • *
  • Posts: 9
    • View Profile
Balls keeping low
« Reply #21 on: 01/04/2007 11:52:33 »
Dear Dr. Beaver,

Please look up a refence before posting. I suggest Tom Smith the definative guide to the laws of cricket and scoring before posting.

There are a certain number of ways to be dismissed in the game of cricket, not just several. It is ok for these insular Americians to be proud of their sad lack of knowledge of the wider world but we have standards to keep.

Would you allow your daughter to marry some one who did not know where square leg is?

Phil
 

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • Posts: 12656
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
Balls keeping low
« Reply #22 on: 01/04/2007 12:17:37 »
Dear Dr. Beaver,

Please look up a refence before posting. I suggest Tom Smith the definative guide to the laws of cricket and scoring before posting.

There are a certain number of ways to be dismissed in the game of cricket, not just several. It is ok for these insular Americians to be proud of their sad lack of knowledge of the wider world but we have standards to keep.

Would you allow your daughter to marry some one who did not know where square leg is?

Phil

Are you inferring that I have omitted ways that a batsman can be out? If so, please enlighten me. (Admittedly, a player can be sent from the field for misconduct but I wouldn't class that as being "out" as it applies equally to the batting & fielding sides.)

P.S. Please use Spell Check before posting. You wouldn't want these Americans to think you're illiterate, would you?  :D

 

The Naked Scientists Forum

Balls keeping low
« Reply #22 on: 01/04/2007 12:17:37 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums