A body moves s metres in a time t seconds so that s = t3 – 3t2 + 8. Find:
i) the velocity, v, after t seconds


ii) its speed at the end of 3 seconds


iii) its acceleration at the end of t seconds its v iv) acceleration at the end of 2 seconds


v) the time is taken when its acceleration is zero.

Respuesta :

Using derivatives, it is found that:

i) [tex]v(t) = 3t^2 - 6t[/tex]

ii) 9 m/s.

iii) [tex]a(t) = 6t - 6[/tex]

iv) 6 m/s².

v) 1 second.

What is the role of derivatives in the relation between acceleration, velocity and position?

  • The velocity is the derivative of the position.
  • The acceleration is the derivative of the velocity.

In this problem, the position is:

[tex]s(t) = t^3 - 3t^2 + 8[/tex]

item i:

Velocity is the derivative of the position, hence:

[tex]v(t) = 3t^2 - 6t[/tex]

Item ii:

[tex]v(3) = 3(3)^2 - 6(3) = 27 - 18 = 9[/tex]

The speed is of 9 m/s.

Item iii:

Derivative of the velocity, hence:

[tex]a(t) = 6t - 6[/tex]

Item iv:

[tex]a(2) = 6(2) - 6 = 6[/tex]

The acceleration is of 6 m/s².

Item v:

t for which a(t) = 0, hence:

[tex]6t - 6 = 0[/tex]

[tex]6t = 6[/tex]

[tex]t = \frac{6}{6}[/tex]

[tex]t = 1[/tex]

Hence 1 second.

You can learn more about derivatives at https://brainly.com/question/14800626