In which situation is no work considered to be done by a force?
oa when the angle between the force and displacement is 180°
o b. when the angle between the force and displacement is 90°
oc when the angle between the force and displacement is 45°
od. when the angle between the force and displacement is 0°

O B. when the angle between the force and displacement is 90°

Explanation:

c

explanation:

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.