Question 1198338: How much force is required to keep a 3.000 lb, car travelling at 45 mph from skidding on the curve of radius of 400 ft.
Found 2 solutions by ikleyn, Alan3354:
Answer by ikleyn(52803)   (Show Source):
You can put this solution on YOUR website! .
How much force is required to keep a 3.000 lb car
travelling at 45 mph from skidding on the curve of radius of 400 ft.
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They want you find the magnitude of the centripetal force.
For it, use the formula
 =  ,
where m is the mass, v is the linear speed, R is the radius, in consistent units.
Convert 45 mph to feet per second 45 mph =  = 66 ft/s.
Convert 3000 lbs to mass by dividing the weight by the gravity acceleration g = 32 ft/s^2
m =  lbs/(ft/s^2).
Now substitute the values into the formula
=  = 1021 lbs. ANSWER
If you ask which force provides it, I will answer you : partly the friction force
and partly the gravity (if the road has a necessary slope to the center of the curve).
Solved.
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The last post-solution notice
these units, lbs, feet and miles, are hopelessly outdated for use in tasks in Physics.
It is just anti-pedagogic and anti-humane to use them in nova days.
I would say, it is just already beyond the red line
that separates educated people from their antipodes.
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An addition, added after viewing the post by Alan.
After the year of 1960, when SI system
was officially established and units " meter ", " kilogram " and " newton "
were introduced for the length, mass and force, respectively,
no one textbook/(problems book) in Physics uses the old units " foot ", " mile " and " pound ".
Answer by Alan3354(69443)  (Show Source):
You can put this solution on YOUR website! Feet and miles (and other units) are "outdated" and inconvenient.
Fluid ounces, cups, teaspoons are silly.
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But, getting rid of feet and nautical miles will be difficult as they're used by all airports, ATC, and pilots world-wide. Ships also use nautical miles and knots.
Altimeter settings are given in inches of mercury, not millibars.
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PS All ATC stations, approach controls, towers and ground controllers must be fluent in English.
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