A softball player moving 3.89 m/s starts a slide, decelerating at -1.44 m/s2
for 4.80 m. How much time does the
slide take? (She does not come to a stop.)

0.119 s is the correct answer to this question.

Explanation:

As mentioned in the question

U=3.89\ m/s

a=-1.44\ m/s^2

S=4.8\ m

Consider the final speed of the softball covering the distance of 4.8m is v

Now using the equation

Putting the value of U, A, S in the previous equation we get

Now again using the equation

v=U+at

where U=intial velocity, t= time

Substituting the value of v, U, a

Hence the slide time is 0.119 s

no. dot product   =0 when vecs at right angles