MHT CET · Physics · Gravitation

A body is projected vertically from the surface of the earth of radius ‘ $R$ ’ with velocity equal to half of the escape velocity. The maximum height reached by the body is

A $R / 5$
B $R / 3$
C $R / 2$
D $R / 4$

Verified Solution

Answer & Solution

Correct Answer

(B) $R / 3$

Step-by-step Solution

Detailed explanation

From mechanical energy conservation

k_{i} + U_{i} = k_{f} + U_{f}

\Rightarrow \frac{1}{2} m . \frac{2 G M}{4 R} - \frac{G M m}{R} = 0 - \frac{G M m}{r} (∵ v_{e} = \sqrt{\frac{2 G M}{R}})

\Rightarrow - \frac{3}{4} . \frac{G M m}{R} = - \frac{G M m}{r}

\Rightarrow r = \frac{4 r}{3} \Rightarrow R + h = \frac{4 R}{3} (h = \frac{R}{3})

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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A body is projected vertically from the surface of the earth of radius ‘ R ’ with velocity equal to half of the escape velocity. The maximum height reached by the body is

Step-by-step Solution

A body is projected vertically from the surface of the earth of radius ‘ $R$ ’ with velocity equal to half of the escape velocity. The maximum height reached by the body is