Question

Maggie rides her bike downhill, starting from rest, accelerates at 2.5 m/s, and reaches the bottom of the hill at a speed of 38 m/s. How long is the hill?

A. 15 seconds
B. 16 seconds
C. 18 seconds
D. 20 seconds

Answer 1

Maggie reaches the bottom of the hill in approximately 15 seconds when starting from rest and accelerating at 2.5 m/s² to a final velocity of 38 m/s.

Step-by-step explanation:

To find out how long it takes Maggie to reach the bottom of the hill, we can use the kinematic equation that relates time, initial velocity, acceleration, and final velocity:

v = u + at

Where:

• v is the final velocity
• u is the initial velocity (which is 0 m/s since she starts from rest)
• a is the acceleration
• t is the time

We are given the final velocity v as 38 m/s, the acceleration a as 2.5 m/s², and we know that Maggie starts from rest, so u is 0 m/s.

Inserting these values into the equation, we get:

38 m/s = 0 m/s + (2.5 m/s²) * t

Solving for t:

t = 38 m/s / 2.5 m/s² = 15.2 seconds

Since we're looking for an answer in whole seconds, we round this to the closest option, which is 15 seconds (Option A).