During motion of a planet from perihelion to aphelion the work done by gravitational force of sun on it is

Question

During motion of a planet from perihelion to aphelion the work done by gravitational force of sun on it is (A) Zero (B) Negative (C) Positive (D) May be positive or negative

Tardigrade Admin · Accepted Answer

According to Kepler's Law of areas, vA < vP vA= speed of planet at aphelion vp= speed of planet at perihelion Now, work done by gravitational force of sun =Δ K . E =(1/2) m(vA2-vP2) ⇒ W text gravitation force is negative.

Q. During motion of a planet from perihelion to aphelion the work done by gravitational force of sun on it is

Zero

Negative

Positive

May be positive or negative

According to Kepler's Law of areas, $v_{A} < v_{P}$
$v_{A} =$ speed of planet at aphelion
$v_{p} =$ speed of planet at perihelion
Now, work done by gravitational force of sun $= Δ K . E = \frac{1}{2} m (v_{A}^{2} - v_{P}^{2})$
$\Rightarrow W_{gravitation force}$ is negative.

Q. During motion of a planet from perihelion to aphelion the work done by gravitational force of sun on it is

Zero

Negative

Positive

May be positive or negative

According to Kepler's Law of areas, vA​<vP​ vA​= speed of planet at aphelion vp​= speed of planet at perihelion Now, work done by gravitational force of sun =ΔK.E=21​m(vA2​−vP2​) ⇒Wgravitation force ​ is negative.

According to Kepler's Law of areas, $v_{A} < v_{P}$
$v_{A} =$ speed of planet at aphelion
$v_{p} =$ speed of planet at perihelion
Now, work done by gravitational force of sun $= Δ K . E = \frac{1}{2} m (v_{A}^{2} - v_{P}^{2})$
$\Rightarrow W_{gravitation force}$ is negative.