Erika was given this problem:The side s(t) of a cube is increasing at a rate of 2 kilometers per hour. At a certain instant t0, the side is 1.5 kilometers. What is the rate of change of the volume V(t) of the cube at that instant?Which equation should Erika use to solve the problem?Choose 1 answer:(A) V(t)=3[s(t)]2(B) V(t)=[s(t)]2(C) V(t)=6[s(t)]2(D) V(t)=[s(t)]3
Q. Erika was given this problem:The side s(t) of a cube is increasing at a rate of 2 kilometers per hour. At a certain instant t0, the side is 1.5 kilometers. What is the rate of change of the volume V(t) of the cube at that instant?Which equation should Erika use to solve the problem?Choose 1 answer:(A) V(t)=3[s(t)]2(B) V(t)=[s(t)]2(C) V(t)=6[s(t)]2(D) V(t)=[s(t)]3
Volume Formula: To find the rate of change of the volume of the cube, we need to use the formula for the volume of a cube, which is the side length cubed, V(t)=[s(t)]3. This is because the volume of a cube is calculated by multiplying the length of the side by itself three times.
Differentiation with Chain Rule: Since the side s(t) is changing with time, we need to differentiate the volume function V(t) with respect to time t to find the rate of change of the volume. This will give us dtdV, the rate of change of the volume with respect to time.
Given Rates and Values: Differentiating V(t)=[s(t)]3 with respect to time t, we use the chain rule which states that dtdV=3[s(t)]2⋅dtds, where dtds is the rate of change of the side length with respect to time.
Substitution and Simplification: We are given that the rate of change of the side length, dtds, is 2 kilometers per hour. We also know that at the instant t0, the side length s(t) is 1.5 kilometers.
Calculation of Rate: Substituting the given values into the differentiated volume formula, we get dtdV=3[1.5]2×2. This simplifies to dtdV=3×2.25×2.
Calculation of Rate: Substituting the given values into the differentiated volume formula, we get dtdV=3[1.5]2×2. This simplifies to dtdV=3×2.25×2. Calculating the value, we get dtdV=3×2.25×2=13.5 km3/hour. This is the rate of change of the volume of the cube at the instant t0.
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