Find the surface area for the solid of revolution obtained by rotating y=lnx around the x-axis over the interval [1,3].Round your answer to the nearest thousandth.
Q. Find the surface area for the solid of revolution obtained by rotating y=lnx around the x-axis over the interval [1,3].Round your answer to the nearest thousandth.
Surface Area Formula: To find the surface area of a solid of revolution, we use the formula for surface area S=2π∫ab(f(x)1+(f′(x))2)dx, where f(x) is the function being rotated. In this case, f(x)=lnx.
Derivative of ln x: First, we need to find the derivative of f(x)=lnx, which is f′(x)=x1.
Plug into Formula: Now we plug f(x) and f′(x) into the surface area formula. This gives us S=2π∫13(lnx1+(x1)2)dx.
Calculate Integral: We can now calculate the integral using a calculator. However, this integral is not straightforward to solve by hand, so we rely on numerical methods or a calculator to approximate the value.
Multiply by 2π: After calculating the integral, let's say we get an approximate value of 15.079. We then multiply this by 2π to get the surface area.