1. A 8.08-nC charge is located 1.92 m from a 3.90-nC point charge.(a) Find the m
ID: 1529760 • Letter: 1
Question
1.
A 8.08-nC charge is located 1.92 m from a 3.90-nC point charge.(a) Find the magnitude of the electrostatic force that one charge exerts on the other.
N
(b) Is the force attractive or repulsive?
attractiverepulsive
2. A molecule of DNA (deoxyribonucleic acid) is 2.26 m long. The ends of the molecule become singly ionized: negative on one end, positive on the other. The helical molecule acts like a spring and compresses 1.05% upon becoming charged. Determine the effective spring constant of the molecule. 3. Four point charges are at the corners of a square of side a as shown in the figure below. Determine the magnitude and direction of the resultant electric force on q, with ke, q, and a in symbolic form. (Let B = 6.0q and C = 6.0q. Assume that the +x-axis is to the right and the +y-axis is up along the page.)
°
magnitude direction°
counterclockwise from the +x-axis a B a a aExplanation / Answer
1)
Apply Columb's law
F = k q1 q2/ r^2
= 9 * 10^9 ( 8.08 * 10^-9) ( 3.9 * 10^-9)/(1.92)^2
=76.93 * 10^-9 N
repulsive force
(2)
the compressed length is
r = l - del l = 2.26 * 10^-6 m - 0.0105* 2.26 * 10^-6 m = 2.23627 * 10^-6 m
compression force is
F = k qe^2/ r^2
from the Hooks law
F = Kdel
K = k qe^2/ r^2 del l
= 9 * 10^9 ( 1.6028 * 10^-19)^2/(2.23627 * 10^-6 m)^2 ( 0.0105* 2.26 * 10^-6 m )
=1.94 * 10^-9 N/m
As per guide lines I worked first two problems , please post remaining post in the next post
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