Answer:
a) 5 N b) 225 N c) 5 N
Explanation:
a) Per Coulomb's Law the repulsive force between 2 equal sign charges, is directly proportional to the product of the charges, and inversely proportional to the square of the distance between them, acting along the line that joins the charges, as follows:
F₁₂ = K Q₁ Q₂ / r₁₂²
So, if we make Q1 = Q1/5, the net effect will be to reduce the force in the same factor, i.e. F₁₂ = 25 N / 5 = 5 N
b) If we reduce the distance, from r, to r/3, as the factor is squared, the net effect will be to increase the force in a factor equal to 3² = 9.
So, we will have F₁₂ = 9. 25 N = 225 N
c) If we make Q2 = 5Q2, the force would be increased 5 times, but if at the same , we increase the distance 5 times, as the factor is squared, the net factor will be 5/25 = 1/5, so we will have:
F₁₂ = 25 N .1/5 = 5 N
<h2>
Answer: 0.17</h2>
Explanation:
The Stefan-Boltzmann law establishes that a black body (an ideal body that absorbs or emits all the radiation that incides on it) "emits thermal radiation with a total hemispheric emissive power proportional to the fourth power of its temperature":
(1)
Where:
is the energy radiated by a blackbody radiator per second, per unit area (in Watts). Knowing 
is the Stefan-Boltzmann's constant.
is the Surface area of the body
is the effective temperature of the body (its surface absolute temperature) in Kelvin.
However, there is no ideal black body (ideal radiator) although the radiation of stars like our Sun is quite close. So, in the case of this body, we will use the Stefan-Boltzmann law for real radiator bodies:
(2)
Where
is the body's emissivity
(the value we want to find)
Isolating
from (2):
(3)
Solving:
(4)
Finally:
(5) This is the body's emissivity
Answer:
C
Explanation:
Formula E=F/C also E=V/d
In this case use the second formula; E=V/d
Data given; E=4N/C d=8m
So v=E X d
V=4x8=32V
k.e=eV= 2X32=64eV
That’s the answer hope you enjoy
Answer:
Tension in the supporting cable is = 4,866 N ≅4.9 KN
Explanation:
First of all, we need to understand that tension is a force, so the motion law
F = Ma applies perfectly.
From Newtons third law of motion, action and reaction are equal and opposite. This means that the force experienced by the elevator, is equal to the tension experienced by the spring.
Parameters given:
Mass of load = 1650 kg
Acceleration of load = ?
The acceleration of the load can be obtained by diving the change in velocity by the time taken. But we need to know the time taken for the motion to 41 m.
Time taken = distance covered / velocity
=
= 3.73 seconds
∴Acceleration = ( initial velocity - final velocity )/ time taken
Note: Final velocity is = 0 since the body came to a rest.
Acceleration =
= 2.95m/
Force acting on the cable = mass of elevator × acceleration of elevator
= 1650 × 2.95 = 4869.5 kg ≅ 4.9 KN