How do I solve this challenging AP Physics mechanics problem?

In summary, the conversation discusses a problem in AP Physics involving a car's reaction time and deceleration. After setting up the problem, graphing the data, and manipulating equations, the person is having trouble solving the problem and seeks help. The solution involves using the formula V^2 = V0^2 +/- 2 * a * x and setting it up for two different cases. The conversation concludes with gratitude for the help received.
  • #1
beeftrax
9
0
I'm doing an independent study in AP Physics, and am having a lot of trouble with the following problem:

"To stop a car, first you require a certain reaction time to begin braking; then the car slows under the constant braking deceleration. Suppose that the total distance moved by your car during these two phases is 56.7 m when its initial speed is 80.5 km/h, and 24.4 m when its initial speed is 48.3 km/h. What are (a) your reaction time and (b) the magnitude of the deceleration" (Fundamentals of Physics 6th ed; Halliday, Resnick, and Walker; pg 29, #37)

I've set the problem up, graphed the data, manipulated a lot of equations, and tried to solve it geometrically. I suspect that I need to use ratios to relate the two different situations, solve for reaction time, and use that to find acceleration, but I can't see how to do it.

Please Help!
 
Physics news on Phys.org
  • #2
Greetings !

Use the formula: V^2 = V0^2 +/- 2 * a * x
V - final velocity
V0 - enitial velocity
-a/+a - de/acceleration
x - distance



How to solve : STOP ! DO NOT READ THIS UNLESS YOU TRIED
TO USE THE ABOVE FORMULA (with some small changes) AND
FAILED ! :wink:





Write the formula for each case. This is how it'll look :

1: V1^2 = V01^2 - 2 * a * (X1 - t * V01)
2: V2^2 = V02^2 - 2 * a * (X2 - t * V02)

X1/X2 - given distances
V01/V02 - given enitial velocities
t - reaction time (unknown)
a - acceleration (unknown)
V1/V2 - final velocities per case => V1 = V2 = 0

Live long and prosper.
 
  • #3
Thanks! You've put my troubled mind at ease.
 

1. What is AP Physics mechanics problem?

AP Physics mechanics problem refers to a type of problem that involves the application of concepts and principles of classical mechanics to solve real-world scenarios. It is a part of the Advanced Placement (AP) Physics curriculum, specifically in the mechanics section.

2. What are some common topics covered in AP Physics mechanics problem?

Some common topics covered in AP Physics mechanics problem include kinematics, Newton's laws of motion, work and energy, momentum, and rotational dynamics. Other topics may also be included depending on the specific curriculum.

3. What are some strategies for solving AP Physics mechanics problems?

Some strategies for solving AP Physics mechanics problems include drawing diagrams to visualize the situation, breaking the problem down into smaller parts, using equations and formulas, and checking for consistency and reasonableness of the answer.

4. How should I prepare for AP Physics mechanics problem in exams?

To prepare for AP Physics mechanics problem in exams, it is important to thoroughly understand the concepts and principles, practice solving different types of problems, and review and familiarize yourself with the relevant equations and formulas. It may also be helpful to seek help from a teacher or tutor if needed.

5. Are there any online resources for practicing AP Physics mechanics problem?

Yes, there are many online resources available for practicing AP Physics mechanics problem. Some examples include practice problems and quizzes on educational websites, video tutorials, and online practice tests. It is important to choose reputable and reliable sources for accurate and helpful practice materials.

Similar threads

  • Introductory Physics Homework Help
Replies
29
Views
2K
  • Introductory Physics Homework Help
Replies
11
Views
689
  • Introductory Physics Homework Help
Replies
4
Views
746
  • Introductory Physics Homework Help
Replies
10
Views
2K
  • Introductory Physics Homework Help
Replies
2
Views
561
  • Introductory Physics Homework Help
Replies
1
Views
2K
  • Introductory Physics Homework Help
Replies
5
Views
1K
  • Introductory Physics Homework Help
Replies
7
Views
2K
  • Introductory Physics Homework Help
Replies
8
Views
2K
  • Introductory Physics Homework Help
Replies
15
Views
3K
Back
Top