The radius of the base of a cylinder is increasing at a rate of 1 meter per hour and the height of the cylinder is decreasing at a rate of 4 meters per hour.At a certain instant, the base radius is 5 meters and the height is 8 meters.What is the rate of change of the volume of the cylinder at that instant (in cubic meters per hour)?Choose 1 answer:(A) −20π(B) −180π(C) 20π(D) 180πThe volume of a cylinder with base radius r and height h is πr2h.
Q. The radius of the base of a cylinder is increasing at a rate of 1 meter per hour and the height of the cylinder is decreasing at a rate of 4 meters per hour.At a certain instant, the base radius is 5 meters and the height is 8 meters.What is the rate of change of the volume of the cylinder at that instant (in cubic meters per hour)?Choose 1 answer:(A) −20π(B) −180π(C) 20π(D) 180πThe volume of a cylinder with base radius r and height h is πr2h.
Volume Formula: The formula for the volume of a cylinder is V=πr2h. We need to find the rate of change of the volume, which is dtdV.
Chain Rule Application: To find dtdV, we use the chain rule from calculus: dtdV=drdV⋅dtdr+dhdV⋅dtdh.
Calculate dV/dr: First, we find dV/dr which is the derivative of V with respect to r. dV/dr=2πrh.
Calculate dhdV: Then we find dhdV which is the derivative of V with respect to h. dhdV=πr2.
Find dtdr and dtdh: Now we plug in the values for dtdr and dtdh. dtdr is 1 meter per hour and dtdh is −4 meters per hour.
Plug in Values: We also plug in the values for r and h at the instant we are considering. r is 5 meters and h is 8 meters.
Calculate dtdV: Now we calculate dtdV using the values we have. dtdV=2π(5 meters)(8 meters)(1 meter/hour)+π(5 meters)2(−4 meters/hour).
Simplify Expression: Simplify the expression. dtdV=80π meters3/hour + (−100π) meters3/hour.
Combine Terms: Combine the terms to find the total rate of change of the volume. dtdV=80π−100π meters3/hour.
Final Result: Simplify the result. dtdV=−20π meters3/hour.
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