Humor: Janitor Turns Heads in Florida With Leaf Blower-Powered Vehicle

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That’s hysterical! My instant gut reaction was “I’ve got all that stuff, I’m going out RIGHT NOW to try it!”, but then my engineering brain kicked in and said “nope, there’s NO WAY it can possibly work”. So I’ll just sit here and watch Star Trek.

I will share it on facebook, though.
 
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My first thought was how does he keep the little wheels from jerking from one side to the other and dumping him on the pavement? I have that wheeled bucket, too, and NO WAY!

Maybe he’s uncommonly balanced? 🤣🤣🤣🤣
 
RhodesianSon said:
Physics doesn’t let that work.
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Not necessarily. Think of the leaf blower as a jet, and the umbrella as a thrust reverser, like they have on aircraft. The leafblower-umbrella combo can generate a net force.

That’s the principle, but I’m not sure it produces enough thrust to propel a man on a mop bucket. I’ll run some experiments and write up my findings in a future post. 🤓
 
Beryllos said:
I’ll run some experiments and write up my findings in a future post. 🤓
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On second thought, just google it.

It looks like the mop bucket is on a motorized skateboard.

Some real skateboarders tried the leafblower-umbrella method and found the thrust to be inadequate.

Another skateboarder used a reinforced umbrella as a sail on a windy day (no leafblower) and was able to travel downwind at moderate speed.
 
Beryllos said:
Not necessarily. Think of the leaf blower as a jet, and the umbrella as a thrust reverser, like they have on aircraft. The leafblower-umbrella combo can generate a net force.
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Yes, necessarily. The force the airstream exerts on the umbrella is exactly balanced by the opposite force that accelerates it out of the blower. The net force is exactly zero.
 
If those two forces were the only forces in the system, you would be right. The leafblower-umbrella system is not closed. It also interacts with the surrounding air.

The leafblower takes still air and accelerates it in the forward direction, which generates a force in the reverse direction.

If the umbrella simply caught the moving air and stopped it, the acceleration of air and the associated force would be equal and opposite.

However, the umbrella doesn’t simply stop the air. It pushes some of it in the opposite direction. The umbrella takes air that’s moving forward, and makes it go backward. Therefore the force on the umbrella is greater.

The difference in force is associated with the net backward acceleration of air.
 
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Here’s a simple thought experiment to illustrate the difference between stopping a moving object and reversing it: When a baseball player catches a moving ball, he has to apply a force on the ball in order to bring it to rest. When he returns the ball, in other words, reverses the momentum of the ball, he applies a force on the ball in the same direction as the first force. The two forces do not cancel.
 
Beryllos said:
It looks like the mop bucket is on a motorized skateboard.
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Yep. This video is fun, but fake. The mop bucket’s wheels are grey for the first 10 seconds, and then black and positioned differently for the rest of the video. If you pause at 11 seconds the skateboard that replaced the bucket’s wheels is pretty obvious.
 
This reminds me of a short story I read as a child where a girl was watching a sailboat race and saw her family dog fall off her brother’s boat and start to drown. She rescued the dog by grabbing an umbrella and using it as a sail to blow herself to where the dog was and get him and then used it to “sail” back. Same principle.
 
Beryllos said:
However, the umbrella doesn’t simply stop the air. It pushes some of it in the opposite direction. The umbrella takes air that’s moving forward, and makes it go backward. Therefore the force on the umbrella is greater.

The difference in force is associated with the net backward acceleration of air.
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You are entirely mistaken.
 
neophyte said:
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Beryllos:
Not necessarily. Think of the leaf blower as a jet, and the umbrella as a thrust reverser, like they have on aircraft. The leafblower-umbrella combo can generate a net force.
Click to expand...
Yes, necessarily. The force the airstream exerts on the umbrella is exactly balanced by the opposite force that accelerates it out of the blower. The net force is exactly zero.
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His arm is absorbing a lot of that energy as you watch his elbow quivering there.
 
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