Answer:
The pushing force she exerts on the sled is equal to the frictional force the ground exerts on the sled.
Step-by-step explanation:
We have given that the brother of the girl is moving with a constant velocity. It means that the acceleration will be zero. Hence, the net force would be zero.
If the net force is zero, then the pushing force exerted on the sled will be equal to the frictional force that ground exerts to the sled.
So, both forces will be equal.