Gravitational Feild

Question 1

What’s the value of thee universal gravitational constant, G

Answer 1

G=6.67×10-¹¹ Nm²Kg-²

Question 2

What exactly is the shape of earth?

Answer 2

The Earth is an oblate spheroid, which means it’s mostly spherical but slightly flattened at the poles and bulging at the equator (due to its rotation).

Question 3

Kepler’s 1st law

Answer 3

It states that the rotational path of a planet around it’s star is an ellipse, with the sun being at one of it’s focus.

Question 4

Kepler’s 2nd law

Answer 4

It states that the planet sweeps out equal area in equal time as it rotates around the star

Question 5

Kepler’s 3rd law

Answer 5

It states that the square of the orbital period is proportional to the cube of the semi-major axis (commonly called the radius) of the ellipse

Question 6

What’s perihelion?

Answer 6

It is the point in the elliptical path of the panets’ rotation that is nearest to the star. Rp

Question 7

What’s Aphelion

Answer 7

It is the point on the elliptical path of a planet that is the farthest from the star. Ra

Question 8

Perihelion + Aphelion?

Answer 8

The sum of both gives the length of the major axis of the elliptical path

Question 9

How was Kepler’s third law proven mathematically?

Answer 9

By equating the centripetal force of the rotating planet to the gravitational force

Question 10

How was Kepler’s 2nd law proven mathematically?

Answer 10

*trace out a triangle from the position of the planet substending an angle θ
*Assuming that tan ∆θ=h/r=∆θ (for very small value of θ
* ∆A=1/r(r∆θ)
*Differentiating both sides with respect to time,t
*Substituting the formula; L=mr²ω, where L is angular momentum
*The resulting equation would be; ∆A/∆t=L/2m, which is practically the mathematical statement of the Kepler’s 2nd law

Question 11

Mathematical statement of Kepler’s third law

Answer 11

*T² = (4π²/GM)(r³),
*Where 4π²/GM is the proportionality constant
*And M is the mass of the star

Question 12

Eccentricity of the elliptical path, e

Answer 12

It is gotten from the formula
ea = a-Rp
e = eccentricity
a = semi-major axis
Rp = perihelion

Question 13

What’s the mass of the sun

Answer 13

It is 1.99×10³⁰ Kg

Question 14

What’s Weightlessness

Answer 14

*Is the situation where a body experience no weight
*It is as a result of the reaction from the ground being less that the weight exerted

Question 15

What’s reaction?

Answer 15

Reaction of a force is a force in opposite direction of the force trying to nullify that force

Question 16

Weight if a body in a lift

Answer 16

*When the lift is moving upward with an acceleration a, the resulting weight is m(a+g)
* When it is moving downward with acceleration a, the weight felt is m(g-a).
*Weightlessness is experienced when a ≥ g, and moving downward

Question 17

What’s mass of the earth?

Answer 17

5.9×10²⁴ Kg