Question

If a rocket is fired with a speed v = near the earth's surface and coasts upwards, its speed in the interstellar space is –

• A.
• B.
• C.
• D.

Answer 1

Answer: (B)

Answer 2

According to law of conservation of energy

$\frac { 1 } { 2 }$ mv² – + 0

$\frac { 1 } { 2 }$ $\frac { 1 } { 2 }$ mv² –

$\mathrm { v } _ { 1 } ^ { 2 }$ = v² – = v² – v_e²

v₁ = $\sqrt { v ^ { 2 } - v _ { e } ^ { 2 } }$ = =