Question

(Assume there is no friction) A bike starts rolling down a hill at 4.3 m/s . After 12 s it reaches the bottom moving at 11.5 m/s. How long was the hill? Express your answer with the correct number of significant digits.

Answer 1

Answer:

$d = 94.8 \ m$

Explanation:

Given data:

Initial velocity, $u = 4.3 \ m/s$

Final velocity, $v = 11.5 \ m/s$

Time, $t = 12 \ s$

The acceleration of the bike can be expressed as,

$a = \frac{v-u}{t}$

$a = \frac{11.5-4.3}{12}$

$a = 0.6 \ m/s^{2}.$

The distance of the hill can be given as,

$d = ut + \frac{1}{2}at^{2}$

$d = 4.3 \times 12 + 0.5 \times 0.6 \times (12)^{2}$

$d = 94.8 \ m.$