Question

Which one of the following statements is correct?

• A. The energy required to rocket an orbiting satellite out of earth’s gravitational influence is more than the energy required to project a stationary object at the same height (as the satellite) out of earth’s influence.
• B. If the zero of potential energy is at infinity, the total energy of an orbiting satellite is negative of potential energy.
• C. The first artificial satellite Sputnik I was launched in the year 1950.
• D. The orbital speed of the SYNCOMS (Synchronous communications satellite) is $3.07 \times 10^{2}ms^{- 1}$

Answer 1

Answer: (D)

The orbital speed of the SYNCOMS (Synchronous communications satellite) is $3.07 \times 10^{2}ms^{- 1}$

Answer 2

The energy required to rocket an orbiting satellite out of earth’s gravitations influence is less than the energy required to project a stationary object at the same height (as the satellite) out of earth’s influence.

Hence, option (1) is incorrect statement.

If zero of potential energy is at infinity, the total energy of an orbiting is negative of its kinetic energy.

Hence, option (2) is an incorrect statement.

The first artificial satellite was launched by Soviet scientists in the year 1957.

Hence, options (3) is an incorrect statement.

The orbital speed of the SYNCOMS is

$v = \frac{2\pi r}{T} = \frac{2 \times 3.14 \times 4.22 \times 10^{7}}{8.64 \times 10^{5}}$

$= 3.07 \times 10^{2}ms^{- 1}$

Hence, option (4) is a correct statement.