Respuesta :

Answer:

[tex] \boxed{\sf Instantaneous \ velocity \ (v) = -3} [/tex]

Given:

Relation between position of an object at time t is given by:

s(t) = -9 - 3t

To Find:

Instantaneous velocity (v) at t = 8

Step-by-step explanation:

To find instantaneous velocity we will differentiate relation between position of an object at time t by t:

[tex] \sf \implies v = \frac{d}{dt} (s(t))[/tex]

[tex] \sf \implies v = \frac{d}{dt} ( - 9 - 3t)[/tex]

Differentiate the sum term by term and factor out constants:

[tex] \sf \implies v = \frac{d}{dt} ( - 9) - 3 (\frac{d}{dt} (t))[/tex]

The derivative of -9 is zero:

[tex] \sf \implies v = - 3( \frac{d}{dt} (t)) + 0[/tex]

Simplify the expression:

[tex] \sf \implies v = - 3( \frac{d}{dt} (t))[/tex]

The derivative of t is 1:

[tex] \sf \implies v = - 3 \times 1[/tex]

Simplify the expression:

[tex] \sf \implies v = - 3 [/tex]

(As, there is no variable after differentiating the relation between position of an object at time t by t so at time t = 8 is of no use.)

So,

Instantaneous velocity (v) at t = 8 is -3