Anand gets into an elevator and travels 50 m straight up in a time of 5 s. He then travels in the opposite direction, straight down, for 70 m in a time of 6 s. What is his average speed and velocity, respectively, over the 11 s period?

A. 10.9 m/s, 1.82 m/s
B. 10.9 m/s, −1.82 m/s
C. 21.8 m/s, 10.9 m/s
D. −10.9 m/s, 5.2 m/s

10.9 m/s, −1.82 m/s

Explanation:

We have,

Anand gets into an elevator and travels 50 m straight up in a time of 5 s. He then travels in the opposite direction, straight down, for 70 m in a time of 6 s.

Total time of journey is 11 seconds.

Total distance is 50 m + 70 m = 120 m

Total displacement is 50 m - 70 m = -20 m

Average speed,

Average velocity,

So, the correct option is (b) 10.9 m/s, −1.82 m/s.

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.