Have you noticed that right before going to commercial, Newscastors rearrange the paperwork on their desks? I wonder if there’s even anything on those sheets of paper. If anyone knows the answer to this, please let me know.

The last two weeks have been very cluttered, but it’s now well into December and MikeDiDonato.com is back in black.

A bunch of things have happened.

#1. MikeDiDonato.com has returned from the dead and has developed new superpowers.

JonAbad mentions a bunch of the excitement in the post previous to this one, I’d also like to point out the exciting filmstrip of features to the left. Provided I keep up with the posting this is the schedule:

Monday: Food!
Tuesday: Defy McQuaid!
Wednesday: House of Rock Video!
Thursday: Miscellaneous (either a movie review, MSPaint image, random hilarity, How-to, etc)
Friday: MSPaint Contest!

Please feel free to participate via the comments, and hopefully much entertainment will be had.

#2. I climbed my first 5.12 cleanly.

Cleanly yes, flawlessly no. But I made it to the top on my own power. For those of you unfamiliar with climbing terms, 5.12 is the difficulty that many equate with the move from intermediate to advanced climbing. It’s a huge breakthrough. 2006 will hopefully see a lot more outdoor climbing, so that I can use the techniques I’ve developed in the gym on real rock. Traditional climbing will follow. and I don’t plan on living in the shadow of 5.13 forever, so really my training has just begun.

It’s good to be back folks.

#48: Smacking the Bullet

The Question

Brandon, Kurt’s co-worker asks
I was wondering something. If a bullet were to be fired at a persons head from, let’s say, 40 meters away, is it possible to use your hand to alter the path of the bullet to miss your head? Pretend the person times it perfectly and strikes the bullet with their hand on the side of the bullet. Would this affect the path enough to miss, or what would happen? Thank you!

The Answer

So, you want to smack a bullet away, like it’s a mosquito. Interesting theory. Let’s do the math.

For this answer, I’m indebted to a party who shall remain nameless, who bolstered my flagging math skills and pointed the way to the answer.

Let’s do the variables first.

v = the velocity of the bullet. For our purposes, we are ignoring wind resistance and the effects of gravity.
t = the time it takes for the bullet to travel to your head.
d = the distance between your hand and your head.
F = the force applied by your hand to the bullet when you whack it.
m = the mass of the bullet.
a = the acceleration imparted by your hand to the bullet when you smack it.
h = half the width of your face. This is the distance you need to move the bullet so it doesn’t hit you.

Now for the equations.

t = d / v

The time it takes to travel a certain distance is the distance divided by the velocity.

F = m * a

But:

a = dv/dt

Acceleration is the deravative of velocity with regards to time.

So,

F = m * dv/dt

The slap will not affect the forward velocity; we are assuming
the strike is perfectly sideways.

So,

F= m * dvy/dt j

Since the forward velocity only affects how hard the bullet has to be
hit, this can be rewritten as

F/m dt = dvy

We are assuming that the force applied is constant for a time duration, so we integrate.
The above equation, when integrated, yields:

F * t / m = vy

How to play with this vy piece?
This one requires a little more calculus than the last:

vy = dy/dt

h = (F*t^2)/(2*m)

Assembling and rearranging:

F = (2*h*m*vx^2) / (d^2)

Okay, we have a workable equation. Let’s fill in some estimated values.

h = 0.1m
d = 1m
m = 0.01kg
v = 1000m/s

F = 20,000 Newtons!

That’s a lot of force. It equates to approximately 4,000 pounds of force.

However, the average person’s fist, when swinging, delivers about 2,000 Newtons to their target. That’s 400 pounds of force.

So, in order to save your pretty face, you’d need to deliver a smack to the bullet that is 10 times more powerful than average, and that’s assuming you hit it directly on the side, and that your hand is impenetrable. Probably unlikely. What would really happen is that your hand would be damaged as well as your head. Not a pretty picture.

This is also not a pretty picture. Think about it.

Welcome to MikeDidonato.com 2k6!

Lots of improvements to the site, some easy to see, some under the hood. Let me give you a quick walkaround:

• Crazy Columns: Now with 50% more columns that the previous version of MikeDidonato.com!
• Fancy Features: A little filmstrip like section in the left column that provides a heads up to that day’s new feature. It might be a new food adventure, a Defying of McQuaid, a video, who knows!
• Quick Thoughts: MikeD wanted a way to post smaller than usual posts, so voila!
• Fresh Sayings: A new tagline will appear whenever you visit Mikedidonato.com. Theoretically, new ones will be added all the time!
• Unread Comments: The sidebar will alert you to new comments throughout the site and the new ones will be highlighted once you get there!
• Live Things: LiveSearch and LiveCalendar for quicker searches via date or keywords!

Known Issues:

• Threaded comments bust out of their cages in Firefox. They are still functional, so its not a dealbreaker.
• Email page is wacky in Internet Explorer.
• LiveSearch is broken in Internet Explorer. You can still type something in and press enter to search normally.

Please comment with your kudos or to let me know of any other bugs that may have escaped our testing!