Calculate the energy in kilowatt hours used by a heater that operates continuously for 30 minutes. The heater has a power rating
1 answer:
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Answer:
a) F_net = 6.48 10⁻¹⁸ ( ), b) x = 0.15 m
Explanation:
a) In this problem we use that the electric force is a vector, that charges of different signs attract and charges of the same sign repel.
The electric force is given by Coulomb's law
F =
Since when we have the two negative charges they repel each other and when we fear one negative and the other positive attract each other, the forces point towards the same side, which is why they must be added.
F_net= ∑ F = F₁ + F₂
let's locate a reference system in the load that is on the left side, the distances are
left side - electron r₁ = x
right side -electron r₂ = d-x
let's call the charge of the electron (q) and the fixed charge that has equal magnitude Q
we substitute
F_net = k q Q ( )
F _net = kqQ ( )
let's substitute the values
F_net = 9 10⁹ 1.6 10⁻¹⁹ 4.50 10⁻⁹ ( )
F_net = 6.48 10⁻¹⁸ ( )
now we can substitute the value of x from 0.05 m to 0.25 m, the easiest way to do this is in a spreadsheet, in the table the values of the distance (x) and the net force are given
x (m) F (N)
0.05 27.0 10-16
0.10 8.10 10-16
0.15 5.76 10-16
0.20 8.10 10-16
0.25 27.0 10-16
b) in the adjoint we can see a graph of the force against the distance, it can be seen that it has the shape of a parabola with a minimum close to x = 0.15 m
Since there is no friction between the ladder and the wall, there can be no vertical force component. That's the tricky part ;)
So to find the weight, divide the 100N <em>normal</em> force by earths gravitational acceleration, 9.8m/s^2
Then;
Draw an arrow at the base of the ladder pointing towards the wall with a value of 30N, to show the frictional force.
So to find the weight, divide the 100N <em>normal</em> force by earths gravitational acceleration, 9.8m/s^2
Then;
Draw an arrow at the base of the ladder pointing towards the wall with a value of 30N, to show the frictional force.