Answer:
when the momentum of the vehicle moving at 30 km/h is higher than the one from the vehicle moving at 60 km/h
Explanation:
It's much harder to stop a freight truck moving at 30 km/h than a hot wheels car moving at 60 km/h.
My educated guess : 21.2 deg
initial velocity (u)=0m/s
final velocity (v)=10m/s
time( t)=5s
acceleration (a)=v-u÷t
acceleration (a)=10-0÷5
acceleration (a)=10÷5
acceleration (a)=2
therefore acceleration (a)=2m/s