The voltage, V (in volts), in an electrical outlet is given as a function of time, t (in seconds), by the function
V(t) = 156cos(120πt)
The derivative is -18720pisin(120pit)
second derivitive is -2246400pi^2cos(120pit)
. To find the Maximum value of the rate of change do I set the second derivative equal to zero?

Question

The voltage, V (in volts), in an electrical outlet is given as a function of time, t (in seconds), by the function 
V(t) = 156cos(120πt)
The derivative is -18720pisin(120pit)
second derivitive is -2246400pi^2cos(120pit) 
. To find the Maximum value of the rate of change do I set the second derivative equal to zero?

anonymous · Answer

maximum and minimum are when the slope of the tangent line is zero

anonymous · Answer

how do i solve sin(120pit)=0?

anonymous · Answer

Take the arcsine of both sides. 

120*pi*t=arcsin(0)=0

t=0

"To find the Maximum value of the rate of change do I set the second derivative equal to zero?"

You will have to test to make sure that whatever value you have isn't a minimum. Technically, you're also supposed to make sure the function is continuous on the interval--but most teachers don't make you worry about it.

anonymous · Answer

hmm..that didnt work