Answer:
He is wrong. 50 m/s is greater than 140 km/h
Explanation:
For comparing the values, both need to be of the same units.
Therefore, converting unit,
140 km/h = 140 x 5/18 m/s = 350/9 m/s or 38.888... m/s(approx.)
As 50>38.888....
Therefore, the student is wrong