A 100 nC charge is placed at the origin. A -50 nC charge is placed at x= 5 cm and a 200 nC is placed at x= -10 cm.
a. What is the net electrostatic force acting on 100 nC charge?
Solution.
"q_1=100\\sdot10^{-9}C;"
"q_2=-50\\sdot10^{-9}C;"
"q_3=200\\sdot10^{-9}C;"
"x_2=5cm=0.05m;"
"x_3=-10cm=-0.1m;"
"F-?;"
"F_{21}=k\\dfrac{q_2q_1}{r_2^2};"
"F_{21}=9\\sdot10^9\\dfrac{50\\sdot10^{-9}\\sdot100\\sdot10^{-9}}{0.05^2}=1.8\\sdot10^{-2}N;"
"F_{31}=k\\dfrac{q_3q_1}{r_3^2};"
"F_{31}=9\\sdot10^9\\dfrac{200\\sdot10^{-9}\\sdot100\\sdot10^{-9}}{0.1^2}=1.8\\sdot10^{-2}N;"
"F=F_{21}-F_{31};"
"F=1.8\\sdot10^{-2}-1.8\\sdot10^{-2}=0N;"
Answer: "F=0N."
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