Higher November 2018 Paper 1 Q3
3. Light travels at \(3 \times 10^5\) kilometres per second.
The circumference of the Earth at the equator is 40 000 km.
Show that, in theory, a beam of light could circle the Earth at the equator more than 7 times in 1 second. [2]
| Scheme | Marks | Comments |
|---|---|---|
| \((3 \times 10^5 =)\ 300\,000\) or \((40\,000 =)\ 4 \times 10^4\) | B1 | |
| \(\dfrac{3\times10^5}{4\times10^4}\) or \(\dfrac{300\,000}{40\,000} = 7.5\) (so more than 7) | B1 | |
| (2) |
Alternative method 1
| Scheme | Marks | Comments |
|---|---|---|
| \(7 \times 40000 = 280\,000\) | B1 | |
| \((3 \times 10^5 =)\ 300\,000\) (so more than 7) | B1 |
Alternative method 2
| Scheme | Marks | Comments |
|---|---|---|
| \(\dfrac{7\times40000}{300000}\) | M1 | |
| \(\dfrac{280000}{300000}\) (which is less than 1) | A1 |