Answer:
t = 300.3 seconds
Explanation:
Given that,
The mass of a freight train, 
Force applied on the tracks, 
Initial speed, u = 0
Final speed, v = 80 km/h = 22.3 m/s
We need to find the time taken by it to increase the speed of the train from rest.
The force acting on it is given by :
F = ma
or

So, the required time is 300.3 seconds.
Answer:
wavelength= 5.35×10cm=0.535m
f= 16000hz
v= wavelength × f= 0.535×16000=8560m/sec
Answer:



- Our final answer is 15 kg .
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