Kurt & Chris G.
20 power cleans 155/105
40 burpees
20 thrusters 155/105
40 pull ups
20 HSPU
40 wall balls
400m run (both partners must complete, may not start until wall balls are complete)
*barbell moves must be unbroken. If bar is dropped or set down must switch.
1 person works at a time!
40 burpees
20 thrusters 155/105
40 pull ups
20 HSPU
40 wall balls
400m run (both partners must complete, may not start until wall balls are complete)
*barbell moves must be unbroken. If bar is dropped or set down must switch.
1 person works at a time!
Post partner, weights and time to comments
Coaches Corner: How does Michelle do?
27 comments:
Michelle, your lift looks good to me. You do a great job of setting up and your back is kept pretty solid through the movement. I'd say try and keep a neutral head verses cranking your neck with the lift - something we all tend to do. Looking strong, girl!
Thx Teresa. I do do that a lot.
11:25 155#
Partnered with Mike Hay
I partnered with the ever awesome Bekah Bus!
11:50
63#, 14# WB to 9' (heaviest ball I've used since the Open)
Bek:HSPU,Reg Pull-up
Nen:Tripod, Blue Band
Nice to see some people I haven't seen in a while!
nice on the wall ball Chris!
Partnered with Cassandra
12:39
70 lb power clean & thruster
Reg pull ups
Tri pod - michelle
Reg HDPU - Cassandra
10 lb wall ball
Thx for the push Cassandra
10:11
1/2 reps- scaled WOD
Box- HSPU
#45 lb (subbed push press for thrusters)
6# WB- ROM
J2B
12:44 partnered with John
- 65# Bar
- 14# WB
- Pike on box for HSPU
Great WOD with the 6am crew!
Partnered with Megan
12:03
55# I did the power cleans, Megan did the thrusters
10# WB Megan to 10', me to 9'
Megan: reg PUs, me: JC2B
Tri-pod HSPU
So happy to be able to come at 9! Fun wod with a fun group!
Thanks for being my partner Rachel! You did awesome! Fun WOD!
11:30 with mike.... Would have been quicker if I didn't start a 2nd set of 10 cleans.... Doh...
105#, box hspu, 20# wb.
Fun wod.
Partnered with Sam. 12:28.
I did 95# for the cleans and the thrusters. Sam did 135#. 30" box pike and 20# on the wall balls.
So, this is a follow up to my preliminary wall ball analysis the other day. This is for you, Sam.
Energy:
The kinetic energy of an object is proportional to the square of its speed.
The gravitational potential energy of an object is proportional to the height of the object above a datum (reference point).
The only way the total energy of an object can change is if work is done on it (neglecting for now thermal considerations - aka heat transfer or any other forms of energy transfer - chemical, nuclear, electrical, etc).
So, during a wallball heave, there are two forces acting on the ball: the applied force of the person heaving the ball up and gravity.
We'll let the bottom of the squat be our datum - our reference point. Some people squat lower than other people, but at the bottom of the squat, we should all be pretty level with each other. At that point, the ball is not moving (no kinetic energy) and we are at our datum, so the gravitational potential energy is zero. This is state #1. The total energy in the ball is 0 foot-pounds.
T1 = kinetic energy at state 1 = 0.
U1 = gravitational potential energy at state 1 = 0.
y1 = height of the ball at state 1. Since this is out datum, y1 = 0.
We then basically do a heave-thruster on the ball releasing the ball from our fingertips at some height y2. At this state, the ball has both kinetic energy (it is moving at some speed v2) and it has gravitational potential energy (since it has risen above our datum). The total work that we performed on the ball is equal to the change of energy of the ball from the 1st energy state to the 2nd energy state. We applied a certain average force on the ball through a distance: y2-y1 = y2 (since y1 = 0).
W(1 to 2) = T2 + U2
The work done from state 1 to state 2 equals the kinetic energy at state 2 plus the gravitational potential energy at state 2. Actually, for completion, we should say that the work done from state 1 to state 2 is the change in the kinetic energy from state 1 to state 2 plus the change in gravitational potential energy from state 1 to state 2. But since state 1 is our datum (T1 = U1 = 0), I left out T1 and U1 from the equation.
Fapp*y2 = 1/2*m*v2^2 - mgy2.
Call this equation 1.
The left side of the equation is the work we applied to the ball (work = force times distance). The right side of the equation is the sum total of the kinetic energy of the ball (1/2*m*v^2) and the potential energy of ball (the work done on the ball by the force of gravity - note the negative sign. g is the acceleration due to gravity and since gravity is directed downwards, the acceleration due to gravity is negative, specifically, -32.2 ft/s^2. Since the ball moved in a direction opposite to the direction of gravity, and since g is taken to be negative, we need a minus sign to indicate the work done ON the ball by the force of gravity. This minus sign cancels with the negative sign contained within g, so -mgy2 is a positive number).
Now, once the ball leaves our finger tips, we don't touch it again until it comes down. The third state here is the state of the ball reaching the top of its trajectory, y3, which should be 10 feet. As the ball rises, it decelerates at a rate of 32.2 ft/s^2. That is, the kinetic energy decreases even while the gravitational potential energy continues to increase. At the top of its trajectory, the kinetic energy is zero, and the potential energy is at its maximum.
T2 + U2 = T3 + U3
1/2*m*v2^2 - mgh2 = 0 - mgh3
By algebra,
v2^2 = -2g(y3-y2)
Call this equation 2.
Then, we plug the right side of equation 2 into v2^2 in equation 1, and do some more algebra.
And we get
Fapp = -mg(y3/y2), or equivalently,
Fapp*y2 = -mgy3.
In other words, the force you need to apply to get the ball to a given height is inversely proportional to the height of the ball when it leaves your finger tips. To be fair however, while Fapp goes down as y2 goes up, the total work that anyone does on the ball to get it to a particular height is equal to the potential energy of the ball at the apex of its trajectory. In other words, short people and tall people are doing the same amount of work on the ball to get the ball up to 10 feet. In order for shorter people to accomplish that work over a shorter distance, they have to apply a greater average force, but everyone is performing the same amount of work to get the ball up to 10 feet.
Now, on the way down, the ball has no kinetic energy at its apex; all of its energy is graviational potential energy. As the ball accelerates downward, its potential energy decreases while the kinetic energy increases.
At state 4, the ball touches the persons hands - we assume at the same height as y2. Thus, the kinetic energy of the ball and the speed of the ball when it first touches the person's hands at state 4 is the same as it was in state 2. Likewise, the potential energy of the ball at state 4 is the same as it was in state 2.
Then, the person applies an upward force to the ball even while he begins to squat again. The person absorbs the kinetic energy of the ball and the potential energy of the ball continues to decrease as the ball continues to go down. At state 5, the ball is back at our datum and its kinetic energy is zero.
So, from state 4 to state 5,
T4 + U4 = T5 + U5 + W(4-5)
1/2*m*v2^2 - mgy2 = -Fapp*y2
Call this equation 3.
Again, the expression for v2^2 of equation 2 into equation 3 and do algebra, and you get
Fapp*y2 = -mgy3.
Again, the force that a short person has to apply in order to stop the ball is greater than the force that a taller person has to apply; however, both the short person and the tall person are doing the same amount of work.
So, with wall balls, both the tall person and the short person injects the same amount of energy into the ball to get the ball to rise to a particular height, and they each absorb the same amount of energy when they catch the ball. But the taller person can apply a smaller force to the ball through his longer movement, while the shorter person has to apply a larger force through a shorter distance. In reality though, when we catch the ball, we generally don't gradually allow the kinetic energy of the ball to fall to zero (and maybe we should in order to be more efficient). We generally stop the ball (bring the kinetc energy right down to zero). Then, we squat and start our next repetition. With this in mind, wall balls are harder on the shorter people, because they absorb much more kinetic energy on the catch then a taller person does. Likewise, the shorter person does have to inject a greater amount of kinetic energy into the ball to get the ball to rise to its apex. For the taller person, a greater percentage of the work is done on changing the potential energy of the ball; he doesn't need to put as much kinetic energy into the ball, and he doesn't absorb as much kinetic energy on the catch. In the extreme cases, consider a 3.5 foot kid and an 8 foot giant. Most of the work done by the 3.5 foot kid is converted to kinetic energy. The 8 foot giant is basically doing thrusters; the ball doesn't even have to leave his hands to get the ball to the 10 foot mark. Thus, the kinetic energy at the top of his wallball thruster is zero.
Everyone is doing the same amount of work. However, and here is the crux of the matter: Power - specifically the power exerted while you actually are touching the ball. Certainly, if people are doing full cycles of wallballs at the same rate, then the shorter person is exerting more average power while his hands are on the ball than the taller person is. On the other hand, the shorter person gets more time to rest when the ball is in the air than the taller person does, so if they are going at the same rate, the average power over an entire cycle is the same. But the shorter person is exerting more average power from state 1 to state 2 and from state 4 to state 5 than the taller person is (everyone rests from state 2 to state 4). The taller person exerts a lower average power during the time that his hands are on the ball than the shorter person exerts. So, which is harder: Running a mile in 6:00 by maintaining an even pace (1:30 per 400 m), or running a mile in 6:00 by running 4 x 400 m - keeping each interval below 65 seconds, and resting (a little) in between intervals? Everyone who does wallballs gets an anaerobic beating, but it is more violent for shorter people, because they have to exert a higher average power while they are touching the ball to keep up with taller people who are cycling wall balls at the same pace. To illustrate the point even more clearly, the shorter you are, the more power you have to exert while touching the ball. Imagine having to run 400's in 55 seconds or faster (and then resting) in order to keep up with someone running 90 second 400's consecutively without rest. Yeah, the total work done is the same and the average power over the entire cycle is the same, but the power exerted during the time that you are actually doing the work is much different.
For another analogy, consider thrusters. Which is harder: Thrusting 100# 10x in 30 seconds or thrusting 200# 5x in 30 seconds. Both people are doing the same amount of work over the same amount of time (assuming that they are the same height and both doing full squats). And the guy who does 5 reps gets to rest more! But there is no question: The power exerted by the guy doing 200# thrusters - during the actual thruster motion is 2x the power exerted by the guy doing 100# thrusters. Their total work is equivalent, and their average power over the 30 seconds is equivalent. But the guy doing 200# thrusters is exerting more power during his actual motion. To make the analogy even more potent, consider a guy who does 2 500# thrusters in 30 seconds! Each of the three individuals are doing the same amount of total work, but obviously that guy who does 2 500# thrusters in 30 seconds is exerting the most power during his actual motion.
Likewise, wall balls are harder for shorter people than for taller people - even though they are doing the same amount of total work over the same amount of total time. The movement is just much more violent for shorter people and calls for greater power exertion during the time that they are actually touching the ball.
Hope you enjoyed this!
WOW Dan. That was way over my head but thanks for confirming that wall balls are harder for short people! Yep!
Fun fun wod. Great work Nen!
Partnered with Kurt S. Used 135 Finished in 10:37. Thanks for doing extra pullups and burpees Kurt.
Partnered with Kolby
9:48 Rx
my brain hurts.
11:07 95#
Fun wod with my girl, Julia!
Partnered with super mom and awesome CrossFit friend Sharon Saks.
11:08
105#
We compliment one another very well and build on the others strengths while fighting through weaknesses. I think i found my co-ed comp partner!
Partnered with Missy C!
13:48 with 75# and 10# wb; I did jpu and tripods, she did kipping and went off a box.
You did an awesome job hanging with those heavy thrusters and I was very grateful for your extra hspu!! :)
By complement each other well, Chris G. means that he did 18/20 thrusters and all but 10 wall balls...He totally carried me through this workout!!
I used 12# wall ball...and I hate to admit it, but it was easier than I remember...maybe I need to start using 14# regularly now...yuk. :-)
LOL
He's really laying it on thick because he wants me to be his comp partner!
And Dan---I'm sorry...I just kept scrolling as soon as I saw a glimmer of algebra...thank you for confirming that WB are harder for short people. You could have just asked any one of us. Thanks for mathematically proving it though. :-)
1/2 reps scaled
35#
jumping pullups
overhead press for HSPU
8# WB to 9ft
10:?
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