Question

which speed is greater 300km/hr or 300m/sec

Answer 1

300 km/hr means 300*5/18 meter per second that is 83.33 metres per second which is lesser than 300 metres per second . therefore 300 metres per second is more than 300 kilometres per hour.
HOPE YOU WILL FIND IT HELPFUL.

Answer 2

300km/hr = (300×1000)/(1×60×60)
= (300×5)/18 = 750/9 = 83.333m/s
By comparing,
300m/s >83.333m/s.
THEREFORE, 300m/s is greater than 300km/hr.