Fast

Fast!!

Ambience: Racing Car, Airplane, Bees

How fast something is actually moving may have very little to do with how fast it seems to be moving. I’m Jim Metzner and this is the Pulse of the Planet

Berman: Since perceived speed is a matter of how many body lengths you move per second, fish can seem very, very fast.

Astronomer Bob Berman is the author of “Zoom How Everything Moves”.

Berman: For example, a sailfish which moves ten body lengths a second, seems very very fast, but a jumbo jet typically comes in when it’s approaching to land, at only one body length per second. That is about 230 feet in a second. So, as you watch a plane come in, these jumbo jets look like they’re hardly moving, because they’re only shifting their entire length once per second, whereas in actuality they’re moving 4 times faster than that fish, which appears to be so much faster. So it’s really a question of perception.

Bacteria are the same. By whipping their tails, called flagella, bacteria typically move 100 body lengths per second. So, are they fast? Well, typically they’ll move only move the width of a human hair in a second. That doesn’t seem very impressive. But it really adds up, so that many germs can cross a kitchen counter in the course of an hour. No wonder diseases spread.

What about insects like bees, which fly so fast we can hardly follow them?

Berman: It’s always a matter of relative to their size. Since bees move at seven miles an hour, well, people can also move at 7 mph when jogging. We never lose track of a person because they’re not shifting their body length by that much, but a bee is.

Pulse of the Planet is made possible by the National Science Foundation and Virginia Tech, inventing the future through a hands-on approach to education and research.

Fast

Perceived speed is a matter of how many body lengths are moving per second!
Air Date:10/21/2016
Scientist:
Transcript:

Fast!!

Ambience: Racing Car, Airplane, Bees

How fast something is actually moving may have very little to do with how fast it seems to be moving. I'm Jim Metzner and this is the Pulse of the Planet

Berman: Since perceived speed is a matter of how many body lengths you move per second, fish can seem very, very fast.

Astronomer Bob Berman is the author of "Zoom How Everything Moves".

Berman: For example, a sailfish which moves ten body lengths a second, seems very very fast, but a jumbo jet typically comes in when it's approaching to land, at only one body length per second. That is about 230 feet in a second. So, as you watch a plane come in, these jumbo jets look like they're hardly moving, because they're only shifting their entire length once per second, whereas in actuality they're moving 4 times faster than that fish, which appears to be so much faster. So it's really a question of perception.

Bacteria are the same. By whipping their tails, called flagella, bacteria typically move 100 body lengths per second. So, are they fast? Well, typically they'll move only move the width of a human hair in a second. That doesn't seem very impressive. But it really adds up, so that many germs can cross a kitchen counter in the course of an hour. No wonder diseases spread.

What about insects like bees, which fly so fast we can hardly follow them?

Berman: It's always a matter of relative to their size. Since bees move at seven miles an hour, well, people can also move at 7 mph when jogging. We never lose track of a person because they're not shifting their body length by that much, but a bee is.

Pulse of the Planet is made possible by the National Science Foundation and Virginia Tech, inventing the future through a hands-on approach to education and research.