Final answer:
The time required for the car to slow from 19 m/s to 3.8 m/s at a constant deceleration of 2.1 m/s² is calculated using the uniform acceleration formula, and the closest given answer is 7.50 seconds.
Step-by-step explanation:
To calculate how many seconds are required before the car is traveling at 3.8 m/s, we can use the formula for uniform acceleration, which relates initial velocity (v0), final velocity (v), acceleration (a), and time (t):
v = v0 + at
We are given that the car slows down from 19 m/s to 3.8 m/s at a constant rate of 2.1 m/s². To find the time (t), we rearrange the formula to solve for t:
t = (v - v0) / a
We can now plug in the values:
t = (3.8 m/s - 19 m/s) / (-2.1 m/s²)
Note the negative acceleration since the car is slowing down.
Calculating the time gives us:
t = (-15.2 m/s) / (-2.1 m/s²) = 7.24 seconds
The closest answer to 7.24 seconds is option c) 7.50 seconds.