Determine the force of gravitational attraction between the earth (m = 5.98 x 10^24kg) and a 70-kg physics student, where the student is at a distance of 6.39 x 10^6 m from earth's
center.

F = 683.8 N

Explanation:

The gravitational force of attraction between the Earth and the student is given by Newton's Law of Gravitation as follows:

where,

F = Force = ?

G = Universal gravitational constant = 6.67 x 10⁻¹¹ Nm²/kg²

m₁ = mass of Earth = 5.98 x 10²⁴ kg

m₂ = mass of student = 70 kg

r = distance between Earth and student = 6.39 x 10⁶ m

Therefore,

F = 683.8 N

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.

snell's law

refractve index = sin incidence / sin refraction