Question

A car entering the freeway accelerates from 10.2 m/s with a constant acceleration of 4.4 m/s 2 . What is the car's final velocity when it merges onto the highway and reaches its cruising speed 4.2 seconds later?

Answer 1

Givens

a = 4.4 m/s^2 This is an acceleration and is positive.

vi = 10.2 m/s

t = 4.2 seconds

vf = ????? The cruising speed in this case is vf.

Formula

a = (vf - vi)/t Notice the 3 givens and what you seek determine the formula

Solve

4.4 m/s^2 = (vf - 10.2)/4.2 Multiply both sides by 4.2

4.4 * 4.2 = vf - 10.2

18.48 = vf - 10.2 Add 10.2 to both sides

18.48 + 10.2 = vf 8.28 is the second best answer.

28.68 = vf This is your cruising speed.

C <<<< Answer