Question

Saki is ice-skating to the left with a velocity of 5\,\dfrac{\text{m}}{\text{s}}5 s m ​ . A steady breeze starts blowing, causing Saki to accelerate leftward at a constant rate of 1.5\,\dfrac{\text{m}}{\text{s}^2}1.5 s 2 m ​ . After 6\,\text s6s, what is Saki's velocity? Answer using a coordinate system where rightward is positive.

Answer 1

Answer:

-14 m/s

Explanation:

Saki's initial velocity is:

$u = - 5 m/s$

where we put a negative sign because the problem tells us to use a coordinte system in which rightward is positive, while Saki's initial velocity is towards the left.

Saki's acceleration due to the breeze is:

$a=-1.5 m/s^2$

Where again, we put a negative sign since the acceleration is leftward.

In order to find Saki's velocity after t = 6 s, we can use the following equation:

$v(t)=u+at$

And substituting all the numbers, we get

$v(6 s)=-5 m/s + (-1.5 m/s^2)(6 s)=-14 m/s$

and the negative sign means the new velocity is leftwards.