Question

A race car traveling at 45 m/s is slowed uniformly at the rate of -1.5 m/s² for 10 seconds. What is its final speed?

A) 30 m/s
B) 45 m/s
C) 20 m/s
D) 60 m/s

Answer 1

By applying the formula for final velocity under constant acceleration, the final speed of the race car is calculated to be 30 m/s after decelerating for 10 seconds at a rate of -1.5 m/s².

Step-by-step explanation:

The question asks for the final speed of a race car that decelerates uniformly over a period of time. We're given the initial speed, the deceleration rate, and the time period of deceleration. The formula for final velocity (v) under constant acceleration (a) is v = u + at, where u is the initial speed and t is time.

Here, initial speed u = 45 m/s, acceleration a = -1.5 m/s² (since it's decelerating, acceleration is negative), and time t = 10 seconds. Plugging these into the equation:

v = 45 m/s + (-1.5 m/s²)(10 s)

v = 45 m/s - 15 m/s

v = 30 m/s

So the final speed of the car after decelerating for 10 seconds is 30 m/s, which corresponds to option A.