Two waves meet and interfere

Physics

1 answer:

Illusion [34]3 years ago

6 0

Answer:

b. amplitude

Explanation:

There are two types of intereference:

- Constructive interference: it occurs when two waves of same frequency meet at a point in phase - this means , the crest of one wave meets with the crest of the other wave. When this occurs, the resultant wave has an amplitude which is equal to the sum of the amplitudes of the two waves.

- Destructive interference: it occurs when two waves of same frequency meet at a point in opposite phase - this means , the crest of one wave meets with the trough of the other wave. When this occurs, the resultant wave has an amplitude which is equal to the difference between the amplitudes of the two waves.

When interference occurs, the other factors of the waves (period, frequency and wavelength) do not change.

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A train is moving along a horizontal track. A pendulum suspended from the roof makes an angle of 4° with the vertical. If g=10m/

nataly862011 [7]

Answer:

Train accaleration = 0.70 m/s^2

Explanation:

We have a pendulum (presumably simple in nature) in an accelerating train. As the train accelerates, the pendulum is going move in the opposite direction due to inertia. The force which causes this movement has the same accaleration as that of the train. This is the basis for the problem.

Start by setting up a free body diagram of all the forces in play: The gravitational force on the pendulum (mg), the force caused by the pendulum's inertial resistance to the train(F_i), and the resulting force of tension caused by the other two forces (F_r).

Next, set up your sum of forces equations/relationships. Note that the sum of vertical forces (y-direction) balance out and equal 0. While the horizontal forces add up to the total mass of the pendulum times it's accaleration; which, again, equals the train's accaleration.

After doing this, I would isolate the resulting force in the sum of vertical forces, substitute it into the horizontal force equation, and solve for the acceleration. The problem should reduce to show that the acceleration is proportional to the gravity times the tangent of the angle it makes.

I've attached my work, comment with any questions.

Side note: If you take this end result and solve for the angle, you'll see that no matter how fast the train accelerates, the pendulum will never reach a full 90°!