Answer:
0.786 Hz, 1.572 Hz, 2.358 Hz, 3.144 Hz
Explanation:
The fundamental frequency of a standing wave on a string is given by

where
L is the length of the string
T is the tension in the string
is the mass per unit length
For the string in the problem,
L = 30.0 m

T = 20.0 N
Substituting into the equation, we find the fundamental frequency:

The next frequencies (harmonics) are given by

with n being an integer number and f being the fundamental frequency.
So we get:



Answer:
520 miles per hour
Explanation:
Let the speed of the Boeing 747 be x miles per hour.
The small airplane covers distance of 780 miles with speed 260 miles per hour.
Also,
After 1.5 hours the Boeing 747 leave the same place and reaches at same time. Both covered distance of 780 miles.
So,
<u>Time taken by Boeing 747 + 1.5 hours = Time taken by small plane.</u>
Also,
Time = Distance/ speed
So,
780 / x + 1.5 = 780/ 260
Solving for x, we get:
<u>x = 520 miles per hour</u>