A parallel-plate air capacitor with a capacitance of 240pF has a charge of magnitude 0.146uC on each plate. The plates have a se
1 answer:
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(a) No, because the mechanical energy is not conserved
Explanation:
The work-energy theorem states that the work done by the engine on the airplane is equal to the gain in kinetic energy of the plane:
(1)
However, this theorem is only valid if there are no non-conservative forces acting on the plane. However, in this case there is air resistance acting on the plane: this means that the work-energy theorem is no longer valid, because the mechanical energy is not conserved.
Therefore, eq. (1) can be rewritten as
which means that the work done by the engine (W) is used partially to increase the kinetic energy of the airplane () and part is lost because of the air resistance (
).
(b) 77.8 m/s
First of all, we need to calculate the net force acting on the plane, which is equal to the difference between the thrust force and the air resistance:
Now we can calculate the acceleration of the plane, by using Newton's second law:
where m is the mass of the plane.
Finally, we can calculate the final speed of the plane by using the equation:
where
is the final velocity
is the initial velocity
is the acceleration
is the distance travelled
Solving for v, we find
Answer:
A) 0.660 g/ml
B) 1.297 ml
C) 0.272 g
Explanation:
Every substance, body or material has mass and volume, however the mass of different substances occupy different volumes. This is where density appears as a physical characteristic property of matter that establishes a relationship between the mass
of a body or substance and the volume
it occupies:
(1)
Knowing this, let's begin with the answers:
<h2 /><h2>Answer A:</h2>Here the mass is and th volume
Solving (1) with these values:
(2)
(3)
In this case the mass of a sample is and its density is
.
Isolating from (1):
(4)
(5)
(5)
In this case the volume of a sample is and its density is
.
Isolating from (1):
(6)
(7)
(8)