A car slows from 17 m/s to 2.0 m/s at a constant rate of 2.1 m/s2. How many seconds are required before the car is traveling at 2.0 m/s?

Divide the speed change by the acceleration rate.

15/2.1 = ___ s

7.14 seconds

To find the time required for the car to reach a speed of 2.0 m/s, we can use the equation of motion:

v = u + at

Where:
v = Final velocity = 2.0 m/s
u = Initial velocity = 17 m/s
a = Acceleration = -2.1 m/s^2 (negative because the car is slowing down)
t = Time

Rearranging the equation, we get:

t = (v - u) / a

Substituting the given values, we have:

t = (2.0 m/s - 17 m/s) / (-2.1 m/s^2)

Calculating the expression, we get:

t = (-15 m/s) / (-2.1 m/s^2)

The units "m/s" in the numerator and denominator cancel out, leaving us with:

t = 15 / 2.1

Using a calculator, we can simplify the expression:

t ≈ 7.14 seconds

Therefore, it takes approximately 7.14 seconds for the car to reach a speed of 2.0 m/s.