Given,
Effort force = 120 N
Load force= 1050 N
Mechanical advantage of a pulley is given by the ratio of load force to the effort force.



Therefore, the mechanical advantage of the given pulley is 8.75.
Answer:
2.When they reach the bottom of the fall
Explanation:
The potential energy of the waterfall is maximum at the maximum height and decreases with decrease in height. Based on the law of conservation of mechanical energy, as the potential energy of the water fall is decreasing with decrease in height of the fall, its kinetic energy will be increasing and the kinetic energy will be maximum at zero height (bottom of the fall).
Thus, the correct option is "2" When they reach the bottom of the fall
That's efficiency. There's no law that it must be stated in percent.
That is meters per second, same as velocity.