Question 1204635
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If you need a formula relating the variables, and/or if you need to find the constant of proportionality, then use the process outlined by the other tutor.<br>
If you only need to answer this question, then there is a much faster path to that answer.<br>
From the first scenario to the second, the radius changes by a factor of 750/650 = 15/13.  The force varies inversely as the radius of the curve, so the required force changes by a factor of 13/15.<br>
From the first scenario to the second, the speed changes by a factor of 30/40 = 3/4.  The force varies directly as the square of the speed, so the force changes by a factor of (3/4)^2 = 9/16.<br>
From the first scenario to the second, the weight of the car does not change, so there is no change to the required force there.<br>
So from the first scenario to the second the force changes by a factor of (13/15)(9/16).<br>
{{{640(13/15)(9/16)=312}}}<br>
ANSWER: 312 pounds<br>