If a wheel with a radius of 80 inches spins at a rate of 50 revolutions per minute, find the approximate linear velocity in miles per hour/ Use 3.14 for pi.

Thank you!

Question

If a wheel with a radius of 80 inches spins at a rate of 50 revolutions per minute, find the approximate linear velocity in miles per hour/ Use 3.14 for pi.

Thank you!

welshfella · Answer

first work out the circumference of the wheel
can you do that?

welshfella · Answer

Circumference = 2 * 3.14 * radius

anonymous · Answer

yes, 2pi r= 502.4

welshfella · Answer

= 2* 3.14 * 80 =  ?

welshfella · Answer

50 revolutions per minute = 50 * 502.4 ins per minute

anonymous · Answer

that's how I get stuck! it's inches to miles and minutes to hours... I've tried it about 5 different ways before I posted. (It's multiple choice, so I know my answers are wrong when they aren't there!)

welshfella · Answer

I'm not at my best today - i just said divide by 60 instead of multiply 
its 50*502.4 * 60 inches per hour 
then as there are 5280 * 12 inches ina mile

mph = 50*502.4 * 60
           -------------
                 5280*12

welshfella · Answer

= 23.79 mph  ?

welshfella · Answer

is that a choice?

anonymous · Answer

ahhhh! Thanks found my error. I was forgetting the 50 back in the original formula. Early for me too, apparently.

welshfella · Answer

lol  ok