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

work: w = fd (given)

work done by chet   =50*1 = 50 j

work done by mika =40*2 = 80 j

work done by sara =30*1.5 = 45 j

work done by bill =60*0.5 = 30 j

students in order from the greatest amount of work done to the least is mika> chet> sara> bill

hence option (b) is correct.

answer: electrons