A pulse was created in a string/slinky of length $4 m$ by a group of $4$ students. They observed that it returned after reflection, at the point of creation, $6$ times in $10$ seconds. They calculated the speed as follows:

Which student has measured the speed correctly?

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answer is C.

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Detailed Solution

A pulse was created in a string/slinky of length

4 m

by a group of

4

students. They observed that it returned after reflection, at the point of creation,

6

times in

10 seconds

. They calculated the speed as given in the table. Student C measured the speed correctly.
The length of the slinkies is

4 m

.
Let the speed of the pulse in the slinky be

v

and the time taken is

t = 10 s

.
We have,

Velocity = Distance / Time

Since the pulse returned 6 times, the distance covered by the pulse is

2 \times 6

.
Then the velocity of the pulse is,

= > v = 2 \times 6 \times 4 / 10

= > v = 4.8 m / s

Hence, the correct speed was calculated by student C.

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