You have probably noticed that carrying a person in a pool of water is much easier than carrying a person through air. To unders
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 However, in this case there is air resistance acting on the plane: this means that the work-energy theorem is no longer valid, because the mechanical energy is not conserved.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
Newton's second law allows us to find the force of the block on the table is 126 N
Newton's second law says that the net force is proportional to the product of the mass and the acceleration of the body
Σ F = m a
Where the bold letters indicate vectors, m is the mass and the acceleration of the body
A free body diagram is a diagram where the forces are represented without the details of the bodies, in the attached we can see a free body diagram of the system.
Let's start by finding the acceleration of the elevator with kinematics
v = v₀ + a t
a =
Where v and v₀ are the current and initial velocity, respectively, at acceleration and t is the time
a =
a = 3.5 m / s²
Let's write Newton's second law for each body
The book
N₂ - W₂ + N₁ = m a
Table
N₁ - W₁ - W₂ = M a
W₁ = Mg
W₂ = mg
N₁ = (M + m) g + M a
N₁ = (10 + 2) 9.8 + 10 3.5
N₁ = 152.6 N
This is the reaction of the earth to the support of the block and the table
N₂ = ma + m g - N₁
N₂ = m ( a +g) - N₁
N₂ = 2 (3.5 + 9.8) - 152.6
N₂ = 26.6 - 152.6
N₂ = -126 N
The negative sign indicates that the direction is opposite to the one assigned, this is the action of the block on the table.
In conclusion using Newton's second law we can find the forces of the block on the table is 126 N
Learn more here: brainly.com/question/19860811
