How efficient is a pulley system if an operator has to pull 2.5m of rope to lift a 250 N pail of water a distance of 4.5 m?

the pulley system is very efficient

Explanation:

Given;

load, L  = 250 N

distance moved by the load, a = 4.5 m

distance moved by the effort, e = 2.5 m

let the force or effort applied = F

Apply the principle of conservation of energy;

F x e = L x a

F = (L x a) / e

F = (250 x 4.5) / 2.5

F = 450 N

The efficient of the pulley system;

E = Output force / Input force

E = (450 x 2.5) / (250 x 4.5)

E = 1 = 100%

Therefore, the pulley system is very efficient

28. evolution

29. environment, survive, offspring  

explanation:

it breaks and dirupture other materials and other sencews from the bottom