Answer:
The charge on the ball bearing 4.507 × 10^-8 C
Explanation:
From Coulomb's law
F = kq1q2/r²
make q2 the subject
q2 = Fr²/kq1
q2 = (1.8×10^-2 × 0.026²) ÷ (9×10^9 × 30×10^-9)
q2 = 4.507 × 10^-8 C
Answer:
3.7 km/h
Explanation:
Let's call v the proper speed of the boat and v' the speed of the water in the river.
When the boat travels in the direction of the current, the speed of the boat is:
v + v'
And it covers 50 km in 3 h, so we can write
(1)
When the boat travels in the opposite direction, the speed of the boat is
v - v'
And it covers 50 km in 5.4 h, so
(2)
So we have a system of two equations: by solving them simultaneously, we find the value of v and v':

Subtracting the second equation from the first one we get:

So, the speed of the water is 3.7 km/h.
That's the 'electrostatic' force.
I think the correct answer is the second option. A circuit describes a closed conducting loop through which an electrical current can flow. It is a path that an electrical current could flow. A circuit could be a closed one or an open circuit. A closed circuit would be a circuit where the current could flow continuously. An open circuit would be a type of circuit where the flow current would only go once and stopped at a particular point since the current has nowhere to go. For a circuit to work, an electric supply should be available to supply the electric current.