vector in physics

The answer is B. straight inward towards the Sun.


The Earth experiences a centripetal force towards the Sun. So it accelerates towards the Sun.

On the other hand, the Earth is moving with uniform horizontal velocity, which is the tangent to the orbit due to no horizontal resultant force.

Therefore, the two vectors sum up and the Earth moves around the Sun.


Just consider the acceleration of the Earth towards the Sun.

Force, F = mv²/r

F = mrω²

Acceleration, a = v²/r

a = rω²


Where

m is mass of the Earth,

v is linear speed of the Earth,

r is the distance between the Earth and the Sun,

ω is the angular speed of the Earth,

ω = 2π/T, where T is the period of the revolution,

ω = v/r

The answer is f.

According the Kepler's Law, the Sun is ONE OF the foci ONLY

Generally, the vector is pointing is such a direction to the central area of the orbit.

B. due to centipetal acc.