A car sits on an entrance ramp to a freeway, waiting for a break in the traffic. Then the driver accelerates with constant acceleration along the ramp and onto the freeway. The car starts from rest, moves in a straight line, and has a speed of 20 m/s(45 mi/h) when it reaches the end of the 120-m-long ramp. (b) How much time does it take the car to travel the length of the ramp?

Video transcript

Hello everyone in this problem. An airplane stands still on the runway to take off. The plane starts from zero initial velocity and heads in a straight path and achieves a speed of 100m per second before taking off the plane covered a distance of 1800 m. What is the time taken by the plane to travel this length of the runway? So I think a good step is to first write out the knowns from this problem. So we know at rest V. I. is equal to 0m/s. Were also given that the final velocity of the airplane is 100 m/s And it travels a total distance of 1800 m. And we want to find the time taken for this traveling. Now among the kinetic equations we recall, we can use any one of them as the F squared equals V. I squared plus two eight dot to access the first one. V. F is equal to V. I plus 80. As the second one. You can also use delta H. Or delta X is equal to V I T, just one half 18 squared. And the 4th 1 delta X is equal to you F. B. I. Over two times 2. Among these cinematic equations were given V. I were giving VF were given delta X. And we want to find T. So it is obvious that we should use this fourth cinematic equation to solve this problem and we can rearrange it as follows. You can just move the F plus V. I over over two term on the other side to get T, which is just two times that the X over VF plus Vi I, and now we can make the substitution. two times 1800 m over. We know that the I. Zero, So it would just be 100 m/s And finally get that T is equal to 36 seconds, which is answer choice. C. I hope this house have a great day.