The position of an object moving along a line is given by p(t) = 7t - cos(( pi )/3t) + 2 p(t)=7tcos(π3t)+2. What is the speed of the object at t = 5 t=5?

1 Answer
Jul 22, 2017

The speed is =6.09ms^-1=6.09ms1

Explanation:

We need

(cosx)'=-sinx

The speed is the derivative of the position

p(t)=7t-cos(pi/3t)+2

v(t)=p'(t)=7+1/3pisin(pi/3t)

The speed at t=5 is

v(5)=7+1/3pisin(5/3pi)

=7+pi/3*-sqrt3/2

=6.09ms^-1