Consider the following problem:The water level under a bridge is changing at a rate of r(t)=40sin(6πt) centimeters per hour (where t is the time in hours). At time t=3, the water level is 91 centimeters. By how much does the water level change during the 4th hour?Which expression can we use to solve the problem?Choose 1 answer:(A) ∫04r(t)dt(B) ∫45r(t)dt(C) ∫34r(t)dt(D) ∫44r(t)dt
Q. Consider the following problem:The water level under a bridge is changing at a rate of r(t)=40sin(6πt) centimeters per hour (where t is the time in hours). At time t=3, the water level is 91 centimeters. By how much does the water level change during the 4th hour?Which expression can we use to solve the problem?Choose 1 answer:(A) ∫04r(t)dt(B) ∫45r(t)dt(C) ∫34r(t)dt(D) ∫44r(t)dt
Define Time Interval: To find the change in water level during the 4th hour, we need to evaluate the rate of change function r(t) from the start to the end of the 4th hour. The 4th hour starts at t=3 and ends at t=4.
Use Integral Expression: The correct expression to use for this problem is the integral of r(t) from t=3 to t=4, which represents the total change in water level during the 4th hour. This corresponds to option (C) ∫34r(t)dt.
Calculate Integral: Now we will calculate the integral of r(t) from t=3 to t=4. ∫3440sin(6πt)dt
Apply Antiderivative Rule: To integrate, we use the antiderivative of sin(kx), which is −k1cos(kx), where k is a constant. In this case, k=6π.∫3440sin(6πt)dt=−π/640[cos(6πt)] | from t=3 to t=4
Simplify Constant Factor: Simplify the constant factor in front of the integral. −π/640=−π240Now we have:−π240[cos(6πt)] | from t=3 to t=4
Evaluate Antiderivative: Evaluate the antiderivative at the upper and lower limits of the integral. −π240[cos(6π⋅4)−cos(6π⋅3)]
Calculate Cosine Values: Calculate the cosine values.cos(6π⋅4)=cos(32π)=−21 (since cos(32π) is in the second quadrant where cosine is negative)cos(6π⋅3)=cos(2π)=0 (since cos(2π) is the cosine of 90 degrees, which is 0)
Substitute Values: Substitute the cosine values into the expression.−π240[−21−0]=π240×21
Simplify Expression: Simplify the expression to find the change in water level during the 4th hour.π240×21=π120 centimeters
More problems from Evaluate definite integrals using the power rule