- twopairacesLv 41 month ago
In the third section, you established that the acceleration of the truck is 3.9 m/s^2. In the fourth section, you established that the time it would take to travel that distance is 7.2 seconds.
The final speed of the truck in this case should simply be the product of the acceleration multiplied by the change in time. Or in equation form: v = a*t. We could also use Work-Energy if you hadn't already solved the fourth part, but I have a feeling that right now you're only in Kinematics.
Which would be 28 m/s, assuming I'm reading the screenshot right. I'd question the use of the extra zeroes in the responses; given the numbers in the original question, the correct answer really should be 30 m/s, as the givens only have one significant figure.
If you're getting that answer and it's still refusing it, contact your instructor.