Question

A drag racer accelerates at 24.3 m/s2 for 3.2 s. It then travels at a constant velocity until it finishes the 400 m race. How long does it take for the drag racer to complete the race? a. 11.4 seconds

b. 8.0 seconds
c. 5.6 seconds
d. 14.2 seconds

Answer 1

The drag racer takes approximately 8.34 seconds to complete the race, with an acceleration phase and a constant velocity phase.

Step-by-step explanation:

To find the time it takes for the drag racer to complete the race, we need to consider two parts of the race: the acceleration phase and the constant velocity phase. In the acceleration phase, the drag racer accelerates at a rate of 24.3 m/s² for 3.2 s. Using the equation v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time, we can find that the final velocity at the end of the acceleration phase is 24.3 m/s² * 3.2 s = 77.76 m/s.

In the constant velocity phase, the drag racer maintains this final velocity. To calculate the time taken in this phase, we can use the equation s = vt, where s is the distance and t is the time. Rearranging the equation to solve for t, we get t = s / v. Plugging in the values, we have t = 400 m / 77.76 m/s ≈ 5.14 s.

Therefore, the total time it takes for the drag racer to complete the race is approximately 3.2 s (acceleration phase) + 5.14 s (constant velocity phase) = 8.34 s.