Answer: Time taken by a sound impulse to travel through an aluminum rod 25 kilometers long is 4.9 seconds.
Solution:
Length of aluminium rod = 25 km = 25000 m (1 km=1000 m)
Time taken by sound to travel through aluminium = 5100 m/s (from the table given)
[tex]speed=\frac{distance}{time}=\frac{25000 m}{\text{time taken}}[/tex]
time taken =[tex]\frac{distance}{speed}=\frac{25000 m}{5100 m/s}=4.9019 seconds\approx 4.9 seconds[/tex]
Hence, the correct option is 4.9 seconds.
