Answer:
37.545 m/s
Explanation:
f' = Actual frequency of horn = 269 Hz
f = Observed frequency of horn = 290 Hz
v = Speed of sound in air = 343 m/s
= Speed of second train = 13.7 m/s
= Speed of first train
From Doppler effect we have

The speed of the first train is 37.545 m/s
Answer:
Mass of the box is 25kg
Explanation:
From Newton's second law of motion
Force= mass. acceleration
With the symbol
F=m.a
m=F/a m=(50N)/(2m/s²)
m=25kg
Answer:
Explanation:
Given
Initial Moment of Inertia 
initial Spin 

Final Moment Moment of Inertia 
Conserving Angular momentum




