A car accelerates uniformly from rest along a straight road and experiences negligible frictional forces. The car travels 15m in the second second of its journey. How far does it travel in the fifth second? (OPTIONS: 15m, 35m, 45m, 75m)
3. The Attempt at a Solution [/B]
This seems really sophomore but I'm not arriving at any of those options. What I did was to consider that 15m was covered in two seconds (though I'm not completely sure if that's what is said, or if it means to say that 15m was covered in that specific second). So 15 / 22 = 3.75 ms-2. Multiplying this by 52 gives 93.75m.
Plan B, assume 15m was covered in the specific second. Using a = (v - u) / t, v = 15ms-1, u = 0 and t = 2, giving 7.5ms-2.
7.5 * 52 = 187.5s.