A rocket is fired with a speed u = 3 g R from the earth surface. What will be its speed at interstellar space?

From conservation of mechanical energy K . E . + P . E . s u r f a c e = K . E . + P . E . i n f i n i t y 1 2 m 3 g R 2 + - G M m R = 1 2 m v ∞ 2 + 0 or v ∞ = 7 g R

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PhysicsGravitationEnergy & PotentialEasy2 minPYQ_2020

PhysicsEasysingle choice

A rocket is fired with a speed $u = 3 \sqrt{g R}$ from the earth surface. What will be its speed at interstellar space?

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Answer:

Solution:

From conservation of mechanical energy

${(K . E . + P . E .)}_{s u r f a c e} = {(K . E . + P . E .)}_{i n f i n i t y}$

$\frac{1}{2} m {(3 \sqrt{g R})}^{2} + (- \frac{G M m}{R}) = \frac{1}{2} m v_{\infty}^{2} + 0$

or $v_{\infty} = \sqrt{7 g R}$

Subject:PhysicsTopic:GravitationSubtopic:Energy & Potential

⏱ 2mℹ️ Source: PYQ_2020

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