Map UNIVERSITY PHYSICS Philip R. KDmad L. ase Two red blood cells each have a ma
ID: 1514208 • Letter: M
Question
Map UNIVERSITY PHYSICS Philip R. KDmad L. ase Two red blood cells each have a mass of 9.05 x 104 kg and carry a negative charge spreed uniformly over heir surfaces. The repulsion arising from the excess charge prevents the cells from clumping together One cell carries -3.00 pC and the other -3.30 pC, and each cell can be modeled as a sphere 3.75 x10 m in radius. If the red blood cells start very far apart and move directly toward each other with the same speed, what initial speed would each need so that they get close enough to just barely touch? Assume that there is no viscous drag from any of the surrounding liqu m/ s What is the maximum acceleration of the cells as they move toward each other and just barey touch? m/ sExplanation / Answer
A)
Aply conservation of energy
gain in kinetic energy = loss of potentail energy
2*(1/2)*m*v^2 = k*q1*q2/(2*r)
v = sqrt(k*q1*q2/(m*2*r))
= sqrt(9*10^9*3*10^-12*3.3*10^-12/(9.05*10^-14*2*(3.75*10^-6) )
= 362 m/s
B) Fmax = k*q1*q2/(2*r)^2
m*a_max = k*q1*q2/(2*r)^2
a_max = k*q1*q2/(m*4*r^2)
= 9*10^9*3*10^-12*3.3*10^-12/(9.05*10^-14*4*(3.75*10^-6)^2)
= 1.75*10^10 m/s^2