Answer:
F = 768 N
Explanation:
It is given that,
Speed of the elevator, v = 3.2 m/s
Grain drops into the car at the rate of 240 kg/min, 
We need to find the magnitude of force needed to keep the car moving constant speed. The relation between the momentum and the force is given by :


Since, the speed is constant,



F = 768 N
So, the magnitude of force need to keep the car is 768 N. Hence, this is the required solution.
The answer is Solvent. The reason is in the wording, 'the substance that does the dissolving.' A solvent does the dissolving, a solute is something that can be dissolved.
Im not exactly sure but I think the answer is techtonic plates collide