Q84 / 90 · JEE Main 2021 (01 Sep Shift 2) · Physics

Two satellites revolve around a planet in coplanar circular orbits in anticlockwise direction. Their period of revolutions are 1 hour and 8 hours respectively. The radius of the orbit of nearer satellite is 2×103 km. The angular speed of the farther satellite as observed from the nearer satellite at the instant when both the satellites are closest is πxradh-1, where x is _______.

Correct answer: 3

Solution

T1=1 hour

⇒ω1==2π rad/hour

T2=8 hours

⇒ω2=π4 rad/hour

R1=2×103 km

As T2∝R3

⇒R2R13=T2T12⇒R2R1=182/3=4⇒R=8×103 km

V1=ω1R1=4π×103 km/h

V1=ω2R2=2π×103 km/h

Relative ω=V1-V2R2-R1=2π×1036×103=π3 rad/hour

x=3

Hence, the correct answer is 3.

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