A boy sledding down a hill accelerates at 1.25 m/s2. If he started from rest, in what distance would he reach a speed of 5.00 m/s?

v = a t

5 = 1.25 * t so t = 4

d = (1/2) a t^2 so d = (1/2)(1.25)(16)

To find the distance the boy would reach a speed of 5.00 m/s, we can use the kinematic equation that relates acceleration, initial velocity, final velocity, and distance:

v^2 = u^2 + 2as

Where:
v = final velocity (5.00 m/s)
u = initial velocity (0 m/s, since the boy starts from rest)
a = acceleration (1.25 m/s^2)
s = distance (what we want to find)

We can rearrange the equation to solve for s:

s = (v^2 - u^2) / (2a)

Substituting the given values:

s = (5.00^2 - 0^2) / (2 * 1.25)

Simplifying the equation:

s = (25.00) / (2.50)

s = 10.00 meters

Therefore, the boy would reach a speed of 5.00 m/s after traveling a distance of 10.00 meters.