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:

94.8 m

Explanation:

The motion of the bike is a uniformly accelerated motion (=constant acceleration), so we can use the following suvat equation:

$s=(\frac{u+v}{2})t$

where:

s is the distance covered

u is the initial velocity

v is the final velocity

t is the time elapsed

For the bike in this problem, we have:

u = 4.3 m/s is the initial velocity

v = 11.5 m/s is the final velocity

t = 12 s is the time

Solving for s, we find the length of the hill:

$s=(\frac{4.3+11.5}{2})(12)=94.8 m$