Question

A string of total mass 3.00×10^-2kg is stretched to a length of 4.9m by applying a tension of 14.20N. You flick the end of the string, sending a pulse to the far end. It reflects back to your hand.

PLEASE SHOW WORK, I REALLY WANT TO KNOW HOW TO DO THIS!

A) How fast is the pulse moving?

B) How much time does it take for the pulse to make the round trip (from your hand to the other end and back again)?

Answer 1

Given that :

total mass of the string, m = 3 x 10^-2 kg

length of the string, L = 4.9 m

Tension in the string, T = 14.2 N

You flick the end of the string, sending a pulse to the far end. It reflects back to your hand.

(A) The pulse moving at a speed which is given as :

using an equation,      v = F /

where, = linear mass density = m / L

= (3 x 10^-2 kg) / (4.9 m)

= 6.12 x 10^-3 kg/m

Now, inserting the values in above eq.

v = (14.2 N) / (6.12 x 10^-3 kg/m)

v = 2.32 x 10³ m²/s²

v = 48.1 m/s

(B) Time taken for the pulse to make the round trip (from your hand to the other end and back again) which is given as :

Distance, x = v t                                                                

(4.9 m) = (48.1 m/s) t

t = 0.101 sec