Quiz - Physics - Displacement

[tursiops]

I've been to Italy once and I'm pretty sure the posted speeds were in km/h rather than m/s. I doubt the highway engineers would be prosecuted if somebody drove through an 80 zone at 80 m/s (288 km/h = 179 mph).

It's nice to think that Italy is totally on the SI system.

 

[TMHeimer]

Units are critical here. 187 lbs divided by 64 lbs salt water per cu ft gives you a displacement of 2.9 cubic feet of salt water, not 2.9 lbs.

Thanks. I meant cubic feet. Do you agree that the math says the answer is 2.92 (and a little more) cubic feet that the answer 2.9 would mean the object would eventually float?

 

[skearse]

UCSB and Electrical Engineering for me, and I couldn't agree more. Never heard of the goalpost thing until just now.

ChemE, RPI and then Wisconsin. Same, and it also came in handy on the PE exam, especially when calculating dimensionless numbers. And although I'd seen the goalpost method before; never heard it referred as that.

 

[rhwestfall]

Maybe goalpost was "new" math, I'm a lot older than that.

Hardly "new math"... No, I'm not near your age (born in 1967), but the "goal post method" was taught in my high school long before me. It was constantly used through high school in the various sciences as well as college. I'll still use it daily in my work. Hence the quick scribble I posted. Yes, for a silly single operation it is not really a great value. I should post some images of more complex ones.....

As to my background, BS-Civil Engineering (University At Buffalo), and registered as a New York State Professional Engineer.

YMMV

 

[scubadada]

Hardly "new math"... No, I'm not near your age (born in 1967), but the "goal post method" was taught in my high school long before me. It was constantly used through high school in the various sciences as well as college. I'll still use it daily in my work. Hence the quick scribble I posted. Yes, for a silly single operation it is not really a great value. I should post some images of more complex ones.....

As to my background, BS-Civil Engineering (University At Buffalo), and registered as a New York State Professional Engineer.

YMMV

13 years, that's a long time, kindergarten through high school or college through fellowship training for me. Teaching of math certainly may have changed along the way. @rhwestfall, you're a young whippersnapper

 

[Storker]

Hardly "new math"... No, I'm not near your age (born in 1967), but the "goal post method" was taught in my high school long before me.

When I was in primary school, the philosophy behind math teaching was changed fundamentally. We went from 1+1=2 and 7x8=56 to basic group theory. Forget carrying the one, you have to regroup the tens. It was a bit of a learning curve.

 

[rhwestfall]

Dimensional Analysis: Why the Factor Label Method is a Life Saver

 

[rhwestfall]

How To Convert Between Units - Ladder Method

 

[rhwestfall]

different names, same thing...

 

[tridacna]

PhD in Math here. None of the previous bickering is Math. It's all petty arithmetic.

Take a look at this if you want real math.

https://www.nature.com/articles/d41586-020-00998-2