Question

The kinetic energies of planets in an elliptical orbit about the Sun, at positions A, B and C are \(K_{A}\), \(K_{B}\) and \(K_{C}\), respectively. AC is the major axis and SB is perpendicular to AC at the position of the Sun as shown in figure. Then

• A. \(K_{B}\lt K_{A}\lt K_{C}\)
• B. \(K_{A}>K_{B}>K_{C}\)
• C. \(K_{A}\lt K_{B}\lt K_{C}\)
• D. \(K_{B}>K_{A}\lt K_{C}\)

Hint:

A planet moves fastest near the Sun and slowest farthest from it, so kinetic energy decreases with distance from the Sun.

Answer 1

The Correct Option is B

Step 1: Energy idea
Total energy is constant. Potential energy is lowest at the closest point, so kinetic energy must be highest there.

Step 2: Compare the options
Only the option with the largest kinetic energy at A and the smallest at C matches this.

Step 3: Final answer
The kinetic energy decreases from A to B to C.

Final Answer:
The kinetic energy decreases from A to B to C. \[ \boxed{\text{(B) }K_{A}>K_{B}>K_{C}} \]