Answer:
c) 
Explanation:
Coulomb's law says that the force exerted between two charges is inversely proportional to the square of distance between them, and is given by the expression:
where k is a proportionality constant with the value 
In this case 
, so we have:
Solving the equation for q, we have:
Replacing the given values:
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Answer:
<h3>62.5N</h3>
Explanation:
The pressure at one end of the piston is equal to the pressure on the second piston.
Pressure = Force/Area
F1/A1 = F2/A2
Given
F1 = 250N
A1 = 2.0m²
A2 = 0.5m²
F2 = ?
Substituting the given values in the formula;
250/2 = F2/0.5
cross multiply
250*0.5 = 2F2
125 = 2F2
F2 = 125/2
F2 = 62.5N
Hence the force needed to lift this piston if the area of the second piston is 0.5 m^2 is 62.5N
Answer: f = - 0.50 m, negative (diverging) lens
Explanation: D-value (diopter ) means 1/f, unit is 1/m. Thus -2.0D
Means f = ( 1/ -2.0 ) m = -0.50 m
