Question

The distance between centre of the earth and moon is 384000 km. If the mass of the earth is $6 \times 10 ^ { 24 }$kg and The speed of the moon is nearly

• A. 1 km / sec
• B. 4 km / sec
• C. 8 km / sec
• D. 11.2 km / sec

Answer 1

Answer: (A)

1 km / sec

Answer 2

Orbital velocity $v = \sqrt { \frac { G M } { r } } = \sqrt { \frac { 6.67 \times 10 ^ { - 11 } \times 6 \times 10 ^ { 24 } } { 38400 \times 10 ^ { 3 } } }$