Question

find the speed of a car at t=4s given distance (meter) is defined by S = t square-6t+15 A) 5m/s B) 6m/s C) 2m/s D) 15m/s With detailed solution (step by step)

Answer 1

Answer:

correct option is c (2m/s)

Explanation:

• given,

$s = {t}^{2} - 6t + 15$

• speed can be calculated by,

$v = \frac{ds}{dt} \\ = \frac{d}{dt} ( {t}^{2} - 6t + 15) \\ = 2t - 6$

• i.e, v=2t-6

therefore,speed at 4th second,

$v = 2t - 6 \\ = 2 \times 4 - 6 \\ = 2$

V(4)=2m/s