SOLUTION: Solve: The force needed to keep a car from skidding on a curve varies jointly as the weight of the car and the square of the car's speed, and inversely as the radius of the curv

This is the general formula for all variation problems:

This force is the .  We will use the letter . So

The  are the weight, , and speed, , squared, which gives 

There is just one , the radius .

So we write the equation using the general formula for all
variation problems:



eliminating the ones that don't apply:

Plug those values in: ,, , 





Solve for k:





So go back to this equation:



and substitute only the value of  



or we can just make it



Now our formula is complete. We are now ready to use it:

That just asks: What is  when , , and 

So we plug those in:

we round that to the nearest pound.

 

Edwin