Answer:
An eating disorder is a serious mental illness, characterised by eating, exercise and body weight or shape becoming an unhealthy preoccupation of someone's life.
It means the speed is constant with a value of 4 units.
Answer:652.05 J
Explanation:
Given
Weight of lifter 
vertical distance move 
Work done in lifting the weight is equal change in Potential Energy of weight
Change in Potential Energy 

therefore work done is equal to
Answer:
Mechanical advantage = 3
Explanation:
You exert a 100-N force on a pulley system to lift 300-N.
The mechanical advantage of the system is given by the ratio of output force to the input force.
Here, output force = 300 N and input force = 100 N
Mechanical advantage,

Mechanical advantage is 3 it means that there are 3 sections of rope support. Hence, this is the required solution.
Base on my research, as of 2004 The U.S. devours about 20 million barrels of oil a day, according to the CIA. But base on Wikipedia, it says that a normal large tanker can only carry around 2 million barrels of oil. So to supply the U.S with this oil per day, it needs 10 normal large oil tankers.