An object's two dimensional velocity is given by v(t) = ( e^t-2t , t-4e^2 )v(t)=(et2t,t4e2). What is the object's rate and direction of acceleration at t=5 t=5?

2 Answers
Mar 7, 2018

The rate of acceleration is =146.4ms^-1=146.4ms1 in the direction of 0.4^@0.4 anticlockwise from the x-axis

Explanation:

The acceleration is the derivative of the velocity

v(t)=(e^t-2t, t-4e^2)v(t)=(et2t,t4e2)

a(t)=v'(t)=(e^t-2, 1)

When t=5

a(5)=(e^5-2, 1)

a(5)=(146.4,1)

The rate of acceleration is

||a(5)||=sqrt(146.4^2+1^2)=146.4ms^-1

The angle is

theta=arctan(1/146.4)=0.4^@ anticlockwise from the x-axis

Mar 7, 2018

Please see below.

Explanation:

As velocity is given by v(t)=(e^t-2t,t-4e^2)

accelaration is (dv)/(dt)=d/(dt)(e^t-2t)hati+d/(dt)(t-4e^2)hatj

or (e^t-2)hati+hatj

Note that -4e^2 is a constant hence its differential is 0.

and at t=5, accelaration is (e^5-2)hati+hatj

Its magnitude is sqrt((e^5-2)^2+1)=sqrt((148.4132-2)^2+1)

= 146.417

and direction is tan^(-1)(1/(e^5-2))=tan^(-1)(1/146.4132)

= 0.39^@