Problem

A cylinder begins with a diameter of 28 yards and a height of 22 yards. If the diameter increases at an instantaneous rate of 2yd/sec and the height decreases at an instantaneous rate of 5yd/sec, determine the rate at which the surface area of the cylinder is changing.

Answer

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Answer

So, the rate at which the surface area of the cylinder is changing is 60πyd2/sec.

Steps

Step 1 :We are given a cylinder with a diameter of 28 yards and a height of 22 yards. The diameter is increasing at a rate of 2 yards per second and the height is decreasing at a rate of 5 yards per second. We are asked to find the rate at which the surface area of the cylinder is changing.

Step 2 :The surface area of a cylinder is given by the formula A=2πr(r+h), where r is the radius and h is the height.

Step 3 :We can differentiate the surface area formula with respect to time to get an expression for the rate of change of the surface area. This will give us a formula in terms of the rates of change of the radius and the height.

Step 4 :Taking the derivative, we get dAdt=2πdhdtr+drdt(2πr+2π(h+r)).

Step 5 :We substitute the given values into the formula: r=14, h=22, drdt=2, and dhdt=5.

Step 6 :Substituting these values in, we find that dAdt=60π.

Step 7 :So, the rate at which the surface area of the cylinder is changing is 60πyd2/sec.

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