Answer: D
Experiment 1 has a confounding variable related to the mass of the rockets. Any variation in mass may cause a discrepancy in the distance traveled.
This is the answer to the question because:
- Both experiments do have a confounding variable.
- Experiment 1 doesn't have to stay constant.
- A double-blind experiment will not do anything to the placebo.
- High blood pressure people will not make the results confusing.
The answer has to be the option D. Hope this helps you!
(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 However, in this case there is air resistance acting on the plane: this means that the work-energy theorem is no longer valid, because the mechanical energy is not conserved.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

It can hurt and harm the body on many different and levels
The magnitude of e.m.f induced in the loop when t = 2 s is 31 Volts.
<h3>emf induced in the loop</h3>
The magnitude of e.m.f induced in the loop is calculated as follows;
emf = dФ/dt
Ф = 6t² + 7t
dФ/dt = 12t + 7
at t = 2 seconds
emf = dФ/dt = 12(2) + 7 = 31 V
Thus, the magnitude of e.m.f induced in the loop when t = 2 s is 31 Volts.
Learn more about emf here: brainly.com/question/24158806
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