Auniform solid cylinder with a radius of 10 cm and a mass of 3.0 kg is rotating about its center with an angular speed of 33.4 rpm. what is its kinetic energy?

0.092 J

Explanation:

Rotational kinetic energy is:

RE = ½ Iω²

where I is the moment of inertia and ω is the angular speed.

For a solid cylinder, I = ½ mr².

RE = ½ (½ mr²) ω²

RE = ¼ mr²ω²

Convert ω from rpm to rad/s.

33.4 rev/min × (2π rad/rev) × (1 min / 60 s) = 3.50 rad/s

Plug in values and solve:

RE = ¼ (3.0 kg) (0.10 m)² (3.50 rad/s)²

RE = 0.092 J

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.