the answer is c in question 7
Answer:

Explanation:
Take at look to the picture I attached you, using Kirchhoff's current law we get:

This is a separable first order differential equation, let's solve it step by step:
Express the equation this way:

integrate both sides, the left side will be integrated from an initial voltage v to a final voltage V, and the right side from an initial time 0 to a final time t:

Evaluating the integrals:

natural logarithm to both sides in order to isolate V:

Where the term RC is called time constant and is given by:

kinematic equation
v squared = u squared + 2 a x s
v= sq root (0 + 2 10 x 65)
i thimk
-- find the horizontal and vertical components of F1.
-- find the horizontal and vertical components of F2.
-- find the horizontal and vertical components of F3.
-- add up the 3 horizontal components; their sum is the horizontal component of the resultant.
-- add up the 3 vertical components; their sum is the vertical component of the resultant.
-- the magnitude of the resultant is the square root of (vertical component^2 + horizontal component^2)
-- the direction of the resultant is the angle whose tangent is (vertical component/horizontal component), starting from the positive x-direction.
Answer:
1, 2 and 3
Explanation:
The most dense substance will settle at the bottom of the cup