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STANDARDPhysics-Gravitation

STANDARD Physics Kepler's Laws MCQ Question

Type: MCQ-conceptual-Medium-Class 11

Figure shows elliptical orbit of a planet P about the sun S. The shaded area SCD is twice the shaded area SAB. If t₁ is the time for the planet to move from C to D and t₂ is the time to move from A to B, then

Question diagram
A

t₁ = t₂

B

t₁ = 2t₂

C

t₁ = 4t₂

D

t₁ > t₂

Correct Answer

Option B

Detailed Explanation

The relationship between the two time periods is t1=2t2t_1 = 2t_2.

Step-by-Step Explanation

Kepler's Second Law (Law of Equal Areas)A line connecting a planet to the Sun sweeps out equal areas in equal periods of time.

This means the ratio of the area swept to the time taken is always constant:AreaTime=Constant\frac{\text{Area}}{\text{Time}}=\text{Constant}Set up the RatiosLet the smaller area SABSAB be equal to AA.

The problem states that area SCDSCD is twice area SABSAB. So, Area SCD=2A\text{Area } SCD = 2A.Apply the FormulaArea SCDt1=Area SABt2\frac{\text{Area\ }SCD}{t_{1}}=\frac{\text{Area\ }SAB}{t_{2}}Substitute the values into the equation:2At1=At2\frac{2A}{t_{1}}=\frac{A}{t_{2}}Simplify the EquationCancel out AA from both sides:2t1=1t2\frac{2}{t_{1}}=\frac{1}{t_{2}}Cross-multiply to solve:t1=2t2t_{1}=2t_{2}

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