Ori was given this problem:The radius r(t) of the base of a cone is increasing at a rate of 10 meters per second. The height h(t) of the cone is fixed at 6 meters. At a certain instant t0, the radius is 1 meter. What is the rate of change of the volume V(t) of the cone at that instant?Which equation should Ori use to solve the problem?Choose 1 answer:(A) V(t)=π[r(t)]2+2π⋅r(t)⋅h(t)(B) V(t)=π[r(t)]2⋅h(t)(C) V(t)=π[r(t)]2+π⋅r(t)[r(t)]2+[h(t)]2(D) V(t)=3π[r(t)]2⋅h(t)
Q. Ori was given this problem:The radius r(t) of the base of a cone is increasing at a rate of 10 meters per second. The height h(t) of the cone is fixed at 6 meters. At a certain instant t0, the radius is 1 meter. What is the rate of change of the volume V(t) of the cone at that instant?Which equation should Ori use to solve the problem?Choose 1 answer:(A) V(t)=π[r(t)]2+2π⋅r(t)⋅h(t)(B) V(t)=π[r(t)]2⋅h(t)(C) V(t)=π[r(t)]2+π⋅r(t)[r(t)]2+[h(t)]2(D) V(t)=3π[r(t)]2⋅h(t)
Volume Function Derivation: The volume V of a cone is given by the formula V=31πr2h, where r is the radius and h is the height. Since the height h(t) is fixed at 6 meters, we can write the volume as a function of time t using the radius r(t).
Radius Function Expression: Given that r(t) is increasing at a rate of 10 meters per second, we can express r(t) as r(t)=r0+10t, where r0 is the initial radius. At the instant t0, the radius r(t0) is 1 meter, so r0=1.
Rate of Change Calculation: To find the rate of change of the volume V(t) at the instant t0, we need to differentiate the volume function with respect to time t. This requires using the correct formula for the volume of a cone.
Substitution of Values: The correct formula for the volume of a cone is V(t)=31π[r(t)]2h. This matches with option (D) V(t)=3π[r(t)]2⋅h(t), since h(t) is constant and equals 6 meters.
Derivative Calculation: Now we will differentiate the volume function V(t) with respect to time t using the chain rule. The derivative of V(t) with respect to t is dtdV=(31)π⋅2r(t)⋅dtdr⋅h, where dtdr is the rate of change of the radius with respect to time.
Final Rate of Change: Substitute the given values into the derivative to find the rate of change of the volume at the instant t0. We have h=6 meters, dtdr=10 meters/second, and r(t0)=1 meter.dtdV=(31)π×2×1 meter ×10 meters/second ×6 meters
Final Rate of Change: Substitute the given values into the derivative to find the rate of change of the volume at the instant t0. We have h=6 meters, dtdr=10 meters/second, and r(t0)=1 meter.dtdV=(31)π×2×1 meter ×10 meters/second ×6 metersPerform the calculation to find the rate of change of the volume at the instant t0.dtdV=(31)π×2×1×10×6dtdV=(31)π×120h=60 cubic meters per second
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