An input for of 80 N is used to lift an object weighing 240 N with a system of pulleys. How far must the rope around the pulleys
1 answer:
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Answer:
(C). The line integral of the magnetic field around a closed loop
Explanation:
Faraday's law states that induced emf is directly proportional to the time rate of change of magnetic flux.
This can be written mathematically as;
is the rate of change of the magnetic flux through a surface bounded by the loop.
ΔФ = BA
where;
ΔФ is change in flux
B is the magnetic field
A is the area of the loop
Thus, according to Faraday's law of electric generators
∫BdL = = EMF
Therefore, the line integral of the magnetic field around a closed loop is equal to the negative of the rate of change of the magnetic flux through the area enclosed by the loop.
The correct option is "C"
(C). The line integral of the magnetic field around a closed loop
1) 5 N
The crate is initially moving, so we must calculate the force of kinetic friction, which is given by:
where
is the coefficient of friction between the crate (made of wood) and the floor (made of wood). The coefficient of kinetic friction between wood and wood is about 0.2.
is the weight of the crate
Substituting the numbers into the formula, we find
2) 5 N
There are two forces acting on the crate along the horizontal direction:
- The force that pushes the crate toward the right, of magnitude
- The force of friction, which acts in the opposite direction (so, towards the left), of magnitude
Since the two forces are in opposite directions, the net force is given by their difference:
3) Yes
The crate is accelerating. In fact, according to Second Newton's Law:
(1)
where Fnet is the net force on the crate, m is its mass, a is its acceleration. We can immediately see that since Fnet is not zero, the acceleration is also non-zero, so the crate is accelerating.
We can even calculate the magnitude of the acceleration. In fact, the mass of the crate is given by:
And by using (1) we find