Flash is the super fast superhero from DC Comics and part of the Justice League. Quicksilver is the super fast superhero from Marvel Comics and sometimes an Avenger.

Comparing these two isn't something new. Geeks have had these "vs" debates since the dawn of time when ancient nerds argued over the strength of Sampson vs. Hercules (that debate is still going on). However, I am going to do something different. I am going contain this argument by only allowing evidence from recent videos. For The Flash, there will be a new show in the fall. Here are a couple of previews of this already online. Video one shows The Flash racing an arrow and – video two has more details. Quicksilver appears in X-Men Days of Future Past. I haven't seen the movie yet, but this clip shows some of Quicksilver's moves.

So, that is my challenge. Using just these clips, who is faster? BASED JUST ON THESE VIDEOS! You are of course free to continue the debate using whatever sources you like in the comment section.

How Fast is the Flash? ———————-

Let me start with the scene where the Flash races an arrow. I am pretty sure that dude shooting an arrow is The Green Arrow. Pretty sure.

When the arrow is launched, it travels about 1.5 meters (just guessing) in three frames (that's 0.083 seconds). This gives the arrow an initial speed of 18 m/s (40 mph). That doesn't seem very fast for an arrow. Typical arrow speeds are around 100 m/s - but I will continue.

Next, the Flash (or is it just "Flash"?) zooms by Green Arrow after a time delay of 1.377 seconds. The arrow finally reaches it's target (or almost) at a time of 2.67 seconds after launch. If the arrow is traveling at a constant speed of 18 m/s, then I can find the distance to the target.

If Flash is going to just get to the target before the arrow, he would have to travel the same distance but in only 1.29 seconds. This gives him a minimum speed of 37 m/s (82 mph). Not very impressive. But maybe he just didn't want to show off too much. Maybe he was only running at half speed. That would give Flash a running speed of 74 m/s. No matter what you do, I don't think you could claim a speed over 100 m/s in this case. And yes, I know. That is just how fast he is running. He could be going slower on purpose. Didn't I already say that?

I was going to look at the part where he runs past the arrow - but this clearly is not in "real time".

Now for the extended Flash trailer. There is a shot in there with a radar gun that shows him running at 702 mph - but I don't want to use that as evidence. That feels like cheating.

Let's skip to the part that shows Flash running around a city as seen from above. I assumed this was in New York City and actually found the location on Google Maps. Just a note, I'm not very familiar with NY but I'm a good guesser. Plus, there aren't many diagonal streets in New York, so that made it a bit easier. Now, I can do a video analysis with a realistic scale using the free Tracker Video Analysis tool. Here is a screenshot from Tracker Video Analysis so you can tell what I am talking about.

Screenshot from Tracker Video Analysis plotting the motion of Flash from Youtube trailer.

Although he turns a bit as he runs, this is his position as a function of time in the direction of the road.

Here you can see that from the slope of this plot Flash has an average x-velocity of about 316 m/s (706 mph). That's much faster than with the arrow scene and in close agreement with the radar gun shot.

Note: If you look at Flash's motion, he makes some turns. Here is the x-y data from Tracker. What kind of acceleration does he have while making these turns?

How Fast is Quicksilver? ————————

That overhead shot in the Flash trailer was perfect. Unfortunately, there is no similar view of Quicksilver in the X-Men trailer. Instead, I will just use something not quite perfect. In this scene, Quicksilver is running around the wall of a circular room (no idea why). It looks like there are water drops falling or something (the camera angle is also sideways).

Screenshot of Tracker Video with analysis of Quicksilver youtube trailer

This part of the clip is clearly in slow motion (otherwise you wouldn't be able to see Quicksilver). But what is the frame rate? If I look at one of these drops of water, I can assume that it has an acceleration of -9.8 m/s2. I can use this to find the real frame rate of the video. If I call this video time units s v (video seconds), then this is a plot of the falling water.

This isn't working. This shows the water slowing down as it moves. That's not good. I suspect the problem is that the water drops are moving back with respect to Quicksilver as he runs giving them an "apparent" motion that slows down. I guess I will need another approach to find the time rate of this slow motion video.

This feels like cheating, but I have no other option. There is a scene where a guard shoots a bullet from his gun in slow motion. What if I assume a bullet speed of a 250 m/s? These pistols look like a 38 Special - of course I am just guessing, but 250 m/s seems like a reasonable place to start.

I made an attempt to guess the dimensions and make a perspective correction on the fired bullet. Here's what that would look like:

Partial perspective correction of fired bullet.

With that correction, I get the following for the trajectory of the bullet.

From the slope of this line, the bullet has a speed of 0.066 m/s v (units of meters per video second to distinguish between time in seconds and time in video seconds). If I assume that is the same as 250 m/s in real speed, I can solve for the relationship between real seconds and video seconds.

Now I can look at a scene with Quicksilver running on the wall. Let's just take one of the wall runs and assume the video is at the same slow motion as the gun shot. Quicksilver takes about one step running in 0.416 seconds. If this step is around 1 meter in distance, he would have a running speed of 2.4 m/s v . Converting this to real seconds, I get

Wow. I mean, I knew Quicksilver was fast, but 9091 m/s (20,000 mph) fast? No, I didn't think that. But let's hold on for a second. Maybe I'm wrong. Wrong as in:

I overestimated the length of the guy's arm for the speed of the bullet. Let's just say I over estimated the size by 25%. That would make the speed 0.75 times smaller.

What if I over estimated the size of the distance Quicksilver moved during this one stride. I think 1 meter is already too short, but let's say it was just 0.75 meter.

I guessed a bullet speed of 250 m/s. What if it was just 200 m/s (couldn't be much slower than that). That would decrease Quicksilver's speed by another factor of 200/250.

Putting all of these lower end estimates in, his speed would decrease by (0.75*.75*.8 = 0.45). This would make Quicksilver's speed 4091 m/s (9151 mph). Still fast.

The Winner ———-

Based on the evidence presented so far in these short clips, Quicksilver is faster. Much faster. Zoom-fast.

Really, I'm happy (even though I am an impartial physicist in the matter). I always liked the Marvel super heroes better than DC. It's just my preference. However, my 8 year old wasn't so pleased. When I told him the results of my study, this is how the discussion went:

8yo: No. No. No. No. There is no way Quicksilver is faster. Flash is faster. I mean, he ran around the whole world in just 5 seconds and then punched Brainiac in the face. Quicksilver couldn't do that. Me: That might be true, but this is just based on the evidence from the videos I found. From what I have seen, Quicksilver is faster. 8yo: Well, Flash was holding back. He wasn't running as fast as he could.

I suspect many of you agree with my 8 year old child.

Physics Homework —————-

The end of the post doesn't dismiss you. I dismiss you, so sit tight and write down this homework.

How can you run over 300 m/s? Suppose you are going exactly 300 m/s. There is an air resistance force pushing on you. You can estimate this by assuming (incorrectly, but it's a start) that the area and drag coefficient are the same for skydiver at terminal velocity of 50 m/s. Now estimate the coefficient of friction between the foot and the ground so that a super hero could run at this constant speed.

Base just on the air resistance force above, how much power would a person need to run this fast (300 m/s)? You can ignore the change in kinetic energy of the legs and stuff. How many candy bars per hour would he have to eat in order to produce this power?

Suppose a normal human has a foot-ground coefficient of friction (static) of 0.7. If they could accelerate at a maximum friction allowed acceleration, how fast would they be going after a distance of 100 meters?

Both Flash and Quicksilver seem to reach running speed rather quickly. Let's say that they both get to the speed that want (whatever that might be) in just 0.1 seconds (which is still a long time for them). What kind of acceleration would they have? How many g's is this? If they can survive an acceleration like this, what kind of punch from Superman or The Hulk could they also survive (serious estimates needed)?

Find some clips from the movie The Incredibles. How fast is Dash? (Dash is the young son of Mr. Incredible)

That's your homework. Chad Orzel (Uncertain Principles) said he would be happy to accept your homework and grade it for you.