A parachutist of mass 20.1 kg jumps out of an airplane at a height of 662 m and lands on the ground with a speed of 7.12 m/s. The acceleration of gravity is 9.8 m/s 2 . How much energy was lost to air friction during this jump

Explanation:

The energy lost due to air friction is equal to the mechanical energy lost by the parachutist during the fall.

The initial mechanical energy of the parachutist (at the top) is equal to his gravitational potential energy:

where

m = 20.1 kg is his mass

is the acceleration due to gravity

h = 662 m is the initial heigth

The final mechanical energy (at the bottom) is equal to his kinetic energy:

where

v = 7.12 m/s is the final speed of the parachutist

Therefore, the energy lost due to air friction is:

real, smaller and upside-down.   so the answer should be b.

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.