Final answer:
The car's acceleration is approximately -0.55 m/s² when it slows down from 23 m/s to rest in 42 seconds, rounded to two significant figures.
Step-by-step explanation:
When a car slows down from 23 m/s to rest in 42 s, the car's acceleration can be calculated using the formula for constant acceleration:
a = (vf - vi) / t,
where a is the acceleration, vf is the final velocity, vi is the initial velocity, and t is the time taken to come to rest.
Given: vf = 0 m/s (car comes to rest), vi = 23 m/s, and t = 42 s.
By substituting the given values into the formula, we have:
a = (0 m/s - 23 m/s) / 42 s
a = -23 m/s / 42 s
a ≈ -0.55 m/s²
The negative sign indicates that the car is decelerating.
Hence, the car's acceleration is approximately -0.55 m/s², rounded to two significant figures.