SOLUTION: A person taps his finger repeatedly. Their finger travels 2.5 cm before making contact with the tabletop. The finger tapping noise is heard once every 0.20 seconds. What is the imp

Algebra ->  Length-and-distance -> SOLUTION: A person taps his finger repeatedly. Their finger travels 2.5 cm before making contact with the tabletop. The finger tapping noise is heard once every 0.20 seconds. What is the imp      Log On


   

Question 1185974: A person taps his finger repeatedly. Their finger travels 2.5 cm before making contact with the tabletop. The finger tapping noise is heard once every 0.20 seconds. What is the impact speed of the finger with the table?
Answer by ikleyn(52800) About Me  (Show Source):
You can put this solution on YOUR website!
.
A person taps his finger repeatedly. Their finger travels 2.5 cm before making contact
with the tabletop. The finger tapping noise is heard once every 0.20 seconds.
What is the impact speed of the finger with the table?
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            This problem is to apply common sense.

            But,  in my view,  its formulation is defective,  because we don't know  (and the problem is silent about it)
            if we can/should consider the move of the finger as uniform or uniformly accelerated.

            What we  CAN  determine,  is the  average speed  of the finger,  instead of the  "impact speed". 


The finger travels  2.5 cm and back  in 0.20  of a second;

so, it travels 2.5 cm in  0.2/2 = 0.1  of a second.


Hence, its average speed is  the_distance%2Fthe_time = 2.5%2F0.1 = 25 cm/s.    ANSWER

Solved.

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If you want to consider the finger's move as uniformly accelerated,  then the estimation for the
impact speed is twice the previous value,  i.e.  50 cm/s.