Physics 0625 · IGCSE · Stars and the Universe

Stars and the Universe — practice question

A galaxy lies 60 million light-years from the Earth. It is receding at a speed of $1300\,\text{km s}^{-1}$. One light-year is approximately $9.5 \times 10^{12}\,\text{km}$. In one year, there are around $3.2 \times 10^{7}$ seconds. Which expression may be used to estimate the age of the Universe in years?

  • A$\frac{60 \times 10^{6} \times 3.2 \times 10^{7}}{1300 \times 9.5 \times 10^{12}}$
  • B$\frac{60 \times 10^{6} \times 9.5 \times 10^{12}}{1300 \times 3.2 \times 10^{7}}$
  • C$\frac{1300 \times 9.5 \times 10^{12}}{60 \times 10^{6} \times 3.2 \times 10^{7}}$
  • D$\frac{1300 \times 3.2 \times 10^{7}}{60 \times 10^{6} \times 9.5 \times 10^{12}}$

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