the circular blade on a saw has a diameter of 7.5 inches and rotates at 2400 revolutions per minute. A) find the angular speed in radians per sec B) Find the linear speed of the saw teeth ( in feet per sec) as the contact the wood being cut. Formulas--> Linear speed= arc length/time= s/t Angular speed= central angle/time arc length s= radius r * central angle(in radians)

the answer in the book is 80pi rad per sec for a and 25pi ft per sec for b but i dont know how to get to that...

There are 2pi for every revolution

so we multipy 2pi * 2400 this is angular speed in minutes, we want is in sec ; so divide by 60 2pi * 2400/60 =80pi

linear speed = radius time angular speed

radius= 7.5/2=3.75 inches=.3125 feet

b)linear speed = radius x angular speed .3125 x 80pi=25 pi

ur wrong you wouldn't divide by 60 you would multiply thus getting the wrong answer

for the min to sec thing

but it matches your answer

the angular speed is wrong you would multiply 60 to convert min to sec

If I run 60 miles per minutes, how many miles do I run in a second?

1 mi per sec?

yeah, did you divide or multiply by 60?

divide

2400 1 min -----*------ = 240/6 rps 1 min 60 sec

okay i got what your saying thanks :) and im sorry that i said you were wrong

no problem, glad to help

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