The variable would be “X”
Answer:
Acceleration of the car will be 
Explanation:
We have given mass of the ball m = 1600 kg
Force in north direction F= 7560 N
Resistance force which opposes the movement of car 
So net force on the car 
According to second law of motion we know that F=ma
So 

He would try to enter as the tide is rising, and leave as the tide is falling. Those things happen at all different times of day during a month.
C) A current is induced in the coiled wire, which lights the light bulb
The moving magnetic field creates electricity which lights the light bulb
Hope it helps!