An artificial satellite is going round the earth, close to its surface. What is the time taken by it to complete one round? Given radius of the earth=6400 km.

Options

A. `14.11 hr`
B. `141.1 hr`
C. `1.414 hr`
D. `0.1414 hr`

Answer

C

Explanation

Here `R=6400 km =6.4xx10^(6)m`,
`g=9.8 ms^(-2)`
Orbital velocity near the earth's surface is `v_(0)=sqrt(gR)=sqrt(9.8xx6.4xx10^(6))=7290 ms^(-1)`
Time period,
`T=(2piR)/(v_(0))=(2xx22xx6.4xx10^(6))/(7xx7290)=5079s`
`=1.411 h`