What is the work input to lift a box of 810 with a 50% mechanical efficiency?

Work input = 1620

Explanation:

Given the following data;

Work output = 810

Efficiency = 50%

To find the work input;

Mathematically, efficiency is given by the formula;

Substituting into the formula, we have;

Cross-multiplying, we have;

Work input = 1620

answer: at 24 february, 2014 the population gets twice of its initial population.

explanation:

since we have given that

the population for alpha city, t years after january 1, 2004 is given as

first we find out the initial population, i.e. t=0,

so, our quadratic equation becomes,

according to question, we have said that if the population has twice its initial population, then it becomes

so, time taken to reach this above mentioned population is given by

now, we know that time can't be negative so, we take t=9.149 years.

hence, at 24 february, 2014 the population gets twice of its initial population.