Larger people pushed faster in current?

[Slow]

So a dead whale will accelerate to current speed faster than a dead minnow?

I won't quote them, it's a bit offensive. . My first post in this thread is the physicist answer (er, because I too am a physicist).

To specifically answer your question: Assuming equal streamlining, the minnow will accelerate to current speed faster. Yes, the force of the current is higher on the whale, but the mass of the whale is also larger...in fact more larger than the force is larger...so the whale accelerates less. This is because mass is proportional to volume, drag is only proportional to cross section. Volume goes up faster than cross section.

 

[KeithG]

Drag is caused by friction... Once you are up to speed there is no more drag. Friction remains.

Ignore the initial condition of getting up to speed. It is a red herring.

 

[tursiops]

I won't quote them, it's a bit offensive. . My first post in this thread is the physicist answer (er, because I too am a physicist).

To specifically answer your question: Assuming equal streamlining, the minnow will accelerate to current speed faster. Yes, the force of the current is higher on the whale, but the mass of the whale is also larger...in fact more larger than the force is larger...so the whale accelerates less. This is because mass is proportional to volume, drag is only proportional to cross section. Volume goes up faster than cross section.

What he said.

The accelerating force on the whale is larger, but the rate of change of velocity is F/m. Time-integrate that and you get velocity; it will have to integrate longer to get up to the current speed.

 

[tursiops]

Drag is caused by friction... Once you are up to speed there is no more drag. Friction remains.

How does that work? What causes the friction if there is no more relative velocity?

 

[KeithG]

How does that work? What causes the friction if there is no more relative velocity?

Friction and drag

 

[BRT]

I won't quote them, it's a bit offensive. . My first post in this thread is the physicist answer (er, because I too am a physicist).

To specifically answer your question: Assuming equal streamlining, the minnow will accelerate to current speed faster. Yes, the force of the current is higher on the whale, but the mass of the whale is also larger...in fact more larger than the force is larger...so the whale accelerates less. This is because mass is proportional to volume, drag is only proportional to cross section. Volume goes up faster than cross section.

Thank you. I agree completely.

 

[BRT]

How does that work? What causes the friction if there is no more relative velocity?

Once you are up to speed there is no more friction.

 

[TMHeimer]

It's pretty technical for me. Would a dead in the water ocean liner (Princess Cruise boat?) and a tennis ball eventually move at the same speed if dropped in the Hudson River?

 

[BRT]

As soon as you are above the surface the wind and air resistance have an effect. At that point who knows!

 

[tursiops]

Friction and drag

The article is correct, IF there is gravity pushing two things together. Where is the force pushing the water against the diver if there is no relative motion?