The answer is D. wavelength!
Answer:

Explanation:
Given
-- initial velocity
--- height
Required
Determine the time to hit the ground
This will be solved using the following motion equation.

Where

So, we have:


Subtract 30.2 from both sides





Solve using quadratic formula:

Where




Split the expression
or 
or 
Time can't be negative; So, we have:


Hence, the time to hit the ground is 1.82 seconds
The wire vibrates back and forth between the poles of the magnet.
The frequency of the vibration is the frequency of the AC supply.

Hi Pupil Here's Your answer :::
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An object moving with constant speed can be accelerated if direction of motion changes. For example, an object moving with a constant speed in a circular path has an acceleration because its direction of motion changes continuously.
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Hope this Helps . . . . . . . . .