c****h
发帖数: 590 | 1 不解，在硬地上动量损失应该小，为什么弹的没用红土高呢？ |
m**l
发帖数: 11854 | 2 不是弹得高，是在水平方向移动同样距离时垂直位置高
【在 c****h 的大作中提到】
: 不解，在硬地上动量损失应该小，为什么弹的没用红土高呢？
|
s***e
发帖数: 7166 | 3 这点破事还用工科理科？红土软，接触球的时候变形，因此球弹地之后水平速度
变慢，除去损耗，剩下的一部分能量转化为垂直方向的速度。
【在 c****h 的大作中提到】
: 不解，在硬地上动量损失应该小，为什么弹的没用红土高呢？
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m**l
发帖数: 11854 | 4 错误。
【在 s***e 的大作中提到】
: 这点破事还用工科理科？红土软，接触球的时候变形，因此球弹地之后水平速度
: 变慢，除去损耗，剩下的一部分能量转化为垂直方向的速度。
|
c****h
发帖数: 590 | 5 呼唤理论帝实验报告。
【在 m**l 的大作中提到】
: 错误。
|
n******r
发帖数: 1247 | 6 红土软，球砸出坑，旋转时和坑壁产生摩擦，所以弹得高
----老肯
【在 c****h 的大作中提到】
: 不解，在硬地上动量损失应该小，为什么弹的没用红土高呢？
|
K****D
发帖数: 30533 | 7 //tear
居然还有人记得。
To be exact, 砸出坑后球顺着坑壁上爬，导致折射角度比硬地偏高，于是弹得高。
【在 n******r 的大作中提到】
: 红土软，球砸出坑，旋转时和坑壁产生摩擦，所以弹得高
: ----老肯
|
w******n
发帖数: 13172 | 8 太牛了。物理学新突破啊
【在 K****D 的大作中提到】
: //tear
: 居然还有人记得。
: To be exact, 砸出坑后球顺着坑壁上爬，导致折射角度比硬地偏高，于是弹得高。
|
L********9
发帖数: 85 | 9 The higher the friction of the surface of the court, the more the spin is
increased when it impacts with the court, and the increase in angular
momentum comes at the expense of linear momentum so the ball bounces at a
more vertical angle than it would on a court with less friction.
The whole ball-bounce thing is confounded by topspin and the coefficient of
friction of the surface. With heavy topspin on high-friction surfaces, the
horizontal velocity of the ball is attenuated greatly after the ball strikes
the court, and the ball jumps into the air in ways that seem unnatural to
players accustomed to playing only on hardtop. |
K****D
发帖数: 30533 | 10 Is this a 原创 or a copy?
One thing for sure, clay's friction is much LOWER than hard court.
of
strikes
【在 L********9 的大作中提到】
: The higher the friction of the surface of the court, the more the spin is
: increased when it impacts with the court, and the increase in angular
: momentum comes at the expense of linear momentum so the ball bounces at a
: more vertical angle than it would on a court with less friction.
: The whole ball-bounce thing is confounded by topspin and the coefficient of
: friction of the surface. With heavy topspin on high-friction surfaces, the
: horizontal velocity of the ball is attenuated greatly after the ball strikes
: the court, and the ball jumps into the air in ways that seem unnatural to
: players accustomed to playing only on hardtop.
|
|
|
w******n
发帖数: 13172 | 11 你说了半天只是说弹跳角度大，还是没说球的绝对高度是不是高，为什么高
of
strikes
【在 L********9 的大作中提到】
: The higher the friction of the surface of the court, the more the spin is
: increased when it impacts with the court, and the increase in angular
: momentum comes at the expense of linear momentum so the ball bounces at a
: more vertical angle than it would on a court with less friction.
: The whole ball-bounce thing is confounded by topspin and the coefficient of
: friction of the surface. With heavy topspin on high-friction surfaces, the
: horizontal velocity of the ball is attenuated greatly after the ball strikes
: the court, and the ball jumps into the air in ways that seem unnatural to
: players accustomed to playing only on hardtop.
|
g*****y
发帖数: 7271 | 12 If surface does not deform, friction direction is strictly horizontal.
Why does it affect the vertical bouncing speed?
of
strikes
【在 L********9 的大作中提到】
: The higher the friction of the surface of the court, the more the spin is
: increased when it impacts with the court, and the increase in angular
: momentum comes at the expense of linear momentum so the ball bounces at a
: more vertical angle than it would on a court with less friction.
: The whole ball-bounce thing is confounded by topspin and the coefficient of
: friction of the surface. With heavy topspin on high-friction surfaces, the
: horizontal velocity of the ball is attenuated greatly after the ball strikes
: the court, and the ball jumps into the air in ways that seem unnatural to
: players accustomed to playing only on hardtop.
|
L********9
发帖数: 85 | 13 the amount of deformation of the clay court or hard court would be minimal
with a DROPPED ball (which only has the vertical component), so almost all
of the bounce would be due to the nature of the ball and not of the surface.
But we are dealing with a tennis in the game, so the increased friction of
clay courts help to 'redirect' the forward momentum of the ball upward
causing a higher bounce. |
L********9
发帖数: 85 | 14 Really? Where do you get that information?
【在 K****D 的大作中提到】
: Is this a 原创 or a copy?
: One thing for sure, clay's friction is much LOWER than hard court.
:
: of
: strikes
|
g*****y
发帖数: 7271 | 15 Apparently, if the ball is perfect sphere and does not deform, friction
won't affect its vertical speed. But the ball will deform. Then it's more
or less similar to 撑杆跳 and the horizontal speed can be converted to
vertical direction.
However, as KennyD said, clay seems to have less friction than hard court.
How to explain that?
Also, clay court does have ball marks. Maybe the dent KennyD says is
caused by the dirt on top, not the surface deformation. But the dent does
contribute to the bouncing?
surface.
【在 L********9 的大作中提到】
: the amount of deformation of the clay court or hard court would be minimal
: with a DROPPED ball (which only has the vertical component), so almost all
: of the bounce would be due to the nature of the ball and not of the surface.
: But we are dealing with a tennis in the game, so the increased friction of
: clay courts help to 'redirect' the forward momentum of the ball upward
: causing a higher bounce.
|
K****D
发帖数: 30533 | 16 From the fact that many players slide on clay courts, but only
a few (Monfils etc) slide on hard court.
【在 L********9 的大作中提到】
: Really? Where do you get that information?
|
g*****y
发帖数: 7271 | 17 Players skid on clay courts but not much on hard courts. It's also much
harder to change direction on clay courts. I guess that is due to less
friction.
【在 L********9 的大作中提到】
: Really? Where do you get that information?
|
K****D
发帖数: 30533 | 18 What happens to the ball mark is:
When the ball lands, it pushes the "dirt" forward slightly,
and forms a small 坑。(Imagine you hit a ball to a 沙坑。)
The clay court base under the "dirt" layer is very solid.
【在 g*****y 的大作中提到】
: Apparently, if the ball is perfect sphere and does not deform, friction
: won't affect its vertical speed. But the ball will deform. Then it's more
: or less similar to 撑杆跳 and the horizontal speed can be converted to
: vertical direction.
: However, as KennyD said, clay seems to have less friction than hard court.
: How to explain that?
: Also, clay court does have ball marks. Maybe the dent KennyD says is
: caused by the dirt on top, not the surface deformation. But the dent does
: contribute to the bouncing?
:
|
a****n
发帖数: 4734 | 19 有数据证明弹的高么？ 现在我能理解和解释的大概就是：红土上，反弹球速比较慢。
是否高。。。我搬小板凳听大侠上课。 |
l*******s
发帖数: 3562 | 20 Monfils为啥可以在硬地上滑步？是他的技术好，还是鞋底和别人不一样？
【在 K****D 的大作中提到】
: From the fact that many players slide on clay courts, but only
: a few (Monfils etc) slide on hard court.
|
|
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L********9
发帖数: 85 | 21 By that logic, then the grass court has less friction than the hard court.
But think again, which court can you roll a glass ball further?
【在 K****D 的大作中提到】
: From the fact that many players slide on clay courts, but only
: a few (Monfils etc) slide on hard court.
|
K****D
发帖数: 30533 | 22 The former.
More precisely, he is braver.
【在 l*******s 的大作中提到】
: Monfils为啥可以在硬地上滑步？是他的技术好，还是鞋底和别人不一样？
|
K****D
发帖数: 30533 | 23 There is a difference between sliding friction and static friction.
On the same surface, static friction is always larger. Only when
the object surpasses a threshold, does it start to slide and receive
sliding friction.
Hard courts obviously has the highest static friction. Also, rolling
friction is a different issue and IMO doesn't apply to the ball
bounce question.
All those explanations on the web claiming that "clay court bounces
higher due to more friction which slows down the ball more" is just
fooling around. It doesn't explain anything at all. The 能量守恒定律
cannot be applied here. You hit a ball to a 沙堆，the bounce height
is ZERO.
【在 L********9 的大作中提到】
: By that logic, then the grass court has less friction than the hard court.
: But think again, which court can you roll a glass ball further?
|
a******g
发帖数: 1538 | 24 如果硬地上铺薄地毯打球，砸不出坑但是摩擦极好，弹跳比红土如何？ |
K****D
发帖数: 30533 | 25 The bounce must suck. 看欧们家地毯有感。
【在 a******g 的大作中提到】
: 如果硬地上铺薄地毯打球，砸不出坑但是摩擦极好，弹跳比红土如何？
|
g*****y
发帖数: 7271 | 26 You should not roll a glass ball. You should slide a box over different
surface for comparison.
【在 L********9 的大作中提到】
: By that logic, then the grass court has less friction than the hard court.
: But think again, which court can you roll a glass ball further?
|
a******g
发帖数: 1538 | 27 那是因为你家地毯下面有padding
【在 K****D 的大作中提到】
: The bounce must suck. 看欧们家地毯有感。
|
c****h
发帖数: 590 | 28 So the higher bounce is due to two factors according to KennyD.
1. the different angle due to the 坑
2. the angular momentum of the ball transferring to the linear momentum, due
to the friction of the dirt
【在 K****D 的大作中提到】
: //tear
: 居然还有人记得。
: To be exact, 砸出坑后球顺着坑壁上爬，导致折射角度比硬地偏高，于是弹得高。
|
