Is it correct plz help

Two red blood cells each have a mass of 9.0 multiply.gif 10-14 kg and carry a negative charge spread uniformly over their surfaces. the repulsion arising from the excess charge prevents the cells from clumping together. one cell carries −2.50 pc of charge and the other −3.10 pc, and each cell can be modeled as a sphere 7.5 μm in diameter. (a) what speed would they need when very far away from each other to get close enough to just touch? assume that there is no viscous drag from any of the surrounding liquid. answer is: 321 m/s how do i find this (b) what is the maximum acceleration of the cells in part (a)? answer is: 1.38e+10 m/s2 how did they find this answer

An object moves from the position +34m to the position -15m in 15 seconds. what is it's total displacement? what is it's average velocity?

When measuring volume, why is it important to use the correct tools and units to attain the greatest accuracy? use specific examples from the lab to support your answer. (5 points)