The speed is 894.775 mile per hour.
What is the speed?
The certain distance travelled in certain time is speed.
Speed = distance/time.
How to calculate the speed in mile per hour?
1 meter per second = 2.23694 mile per hour
Therefore, 400 meter per second = (400*2.23694) mile per hour
=894.775.
Learn more about speed here :
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