Verified answer

Weight = mass * g

On the earth, g = 9.8 m/s^2

Weight = 10 * 9.8 = 98 N

Let’s determine the value of g on this planet.

70 = 10 * g, g = 7 m/s^2

The unit of g is m/s^2. This the unit for acceleration.

Now let me show you how g relates to the equation of the “Universal gravitational force of attraction”.

Fg = (G * M * m) ÷ d^2

And

Force = m * a

Set these 2 equations equal to each other.

(G * M * m) ÷ d^2 = m * a

Divide both sides by m

(G * M) ÷ d^2 = a

“a” is the acceleration. so g = a

This is the equation for g

(G * M) ÷ d^2 = g

G = 6.67 * 10^-11, M is the mass of the planet

d is the distance from the center of mass one to the center of mass of the other object.

In this problem, the 2 objects are a planet and a person. Since the person is on the surface of the planet, d is the radius of the planet.

On this planet g = 7 m/s^2 and r = 100 km = 1 * 10^5 meters

(6.67 * 10^-11 * M) ÷ (1 * 10^5)^2 = 7

Solve for M