Explanation:
It is given that,
Distance between wires, d = 3.5 mm = 0.0035 m
Power of light bulb, P = 100 W
Potential difference, V = 120 V
(a) We need to find the force per unit length each wire of the cord exert on the other. It is given by :

Power, P = V × I

This gives, 


(b) Since, the two wires carry equal currents in opposite directions. So, teh force is repulsive.
(c) This force is negligible.
Hence, this is the required solution.
Resolving vectors question. See diagram enclosed.
Answer:
Mass of the cart = 146 kg
Explanation:
A cart is pulled by a force of 250 N at an angle of 35° above the horizontal.
The cart accelerates at 1.4 m/s² horizontally.
Horizontal force = Fcosθ = 250 cos35° = 204.79N
We have F = ma
Substituting
204.79 = m x 1.4
m = 146.28 kg = 146 kg
Mass of the cart = 146 kg