Answer: 129,600kg/day
In this question, you are given the river flow (30m3/s) and the salt concentration. Then to determine the amount of salt carried, you simply need to multiply the flow with concentration. Be careful because the unit in this question is different and need to be converted. The equation would be:
Salt = river flow x salt concentration
Salt = 30m3/s x 1000L/m3 x 50mg/L = 1,500,000mg/second
Then convert it into kg/day
Salt= 1,500,000mg/second x 10^-6 kg/mg x (3600 second/hour) x (24 hour/day)= 129,600kg/day
Transformer contains two coils: primary and secondary. They allow change of voltage to lower or higher value. In first case we have step-down and in second case we have step-up transformer.
Formula used for transformer is:

Where:N1 = number of turns on primary coilN2 = number of turns on secondary coilV1 = voltage on primary coilV2 = voltage on secondary coil
In a step-down transformer primary coil has more turns than secondary coil. So the ratio 1:38 means that for each turn on secondary coil we have 38 turns on primary coil.
We can solve the equation for V2:

Secondary coil provides voltage of 3.16V.
Answer:
B) 
Explanation:
The electric force between charges can be determined by;
F = 
Where: F is the force, k is the Coulomb's constant,
is the value of the first charge,
is the value of the second charge, r is the distance between the centers of the charges.
Let the original charge be represented by q, so that;
= 2q
= 
So that,
F = 
x 
= 2q x
x 
=
x 
=
x 
F =
x 
The electric force between the given charges would change by
.
Answer:
20573.67N
Explanation:
Given;
mass (m) of the car = 2130kg
angle of inclination Θ = 15⁰
The normal force (F) on the car is given by
F = mgcosΘ
where g is the acceleration due to gravity.
Taking g as 10
and substituting the values of m and Θ into the equation. We have;
F = 2130 x 10 x cos 15⁰
F = 2130 x 10 x 0.9659
F = 20573.67N
Therefore the normal force on the car is 20573.67N