An object accelerates from rest, with a constant acceleration of 4.2 m/s^2, what will its velocity be after 3.1 s?

May someone explain how to do this question?

The energy of a photon was found to be 3.38 × 10–19 j. planck’s constant is 6.63 × 10–34 j • s. which color of light corresponds to this photon?

Alandscaper is shopping for landscaping materials. she wants to use materials through which water flows easily. which materials should she choose? check all that apply. clay gravel granite rocks with cracks loosely packed soil