Final answer:
The initial velocity of the roller coaster is approximately 0.04 mi/h, which is calculated using the final velocity, acceleration, and the time during which the acceleration occurs.
Step-by-step explanation:
The question asks for the roller coaster's initial velocity given a top velocity, acceleration rate, and the time over which this acceleration occurs. To find the initial velocity, we can use one of the kinematic equations of motion:
v = u + at
In this equation, v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time. We can rearrange this to solve for the initial velocity:
u = v - at
Using the values given:
- Final velocity, v = 149 mi/h
- Acceleration, a = 30.4 mi/h/s
- Time, t = 4.90 s
u = 149 mi/h - (30.4 mi/h/s × 4.90 s)
u = 149 mi/h - 148.96 mi/h
u = 0.04 mi/h
The roller coaster's initial velocity is approximately 0.04 mi/h, which is close to being from rest.