An object's two dimensional velocity is given by v(t) = ( t^3, t-t^2sin(pi/8)t)v(t)=(t3,tt2sin(π8)t). What is the object's rate and direction of acceleration at t=3 t=3?

1 Answer
Apr 1, 2017

The rate of acceleration is =27.63ms^-1=27.63ms1 in the direction of =167.69=167.69º

Explanation:

The velocity is

v(t)=(t^3,t-t^2sin((pi/8)t))v(t)=(t3,tt2sin((π8)t))

Acceleration is the first derivative of the velocity

a(t)=(dv(t))/dt=(3t^2,1-2tsin(pi/8)t-t^2(pi/8)cos(pi/8)t)a(t)=dv(t)dt=(3t2,12tsin(π8)tt2(π8)cos(π8)t)

When t=3t=3

a(3)=(dv(3))/dt=(27,1-6sin(3/8pi)-(9/8pi)cos(3/8pi))a(3)=dv(3)dt=(27,16sin(38π)(98π)cos(38π))

=(27,1-5.54-1.35)=(27,15.541.35)

=(27,-5.89)=(27,5.89)

The object rate of acceleration is

=sqrt((27^2)+(-5.89)^2)=(272)+(5.89)2

=27.63ms^-2=27.63ms2

The direction is

=arctan(-5.89/27)=arctan(5.8927)

The angle is in the 2nd quadrant and is

=167.69=167.69º