Kinematics Problem: Get Help Solving

In summary, I used y for forward motoring step distance, y-x for reverse motoring step, t for time of one of each. I found x and y by dividing total distance by (2y-x).
  • #1
HP-Physics
7
0
Homework Statement
Calculate the distance that the driver has traveled in the process.
Relevant Equations
A group of n people needs to move from point A to point B about a distance AB=l apart, but they only have a bike and only one of them is capable of motorcycling (called the driver). The bike has only 2 seats. For everyone to depart from A and arrive in B at the same time, they decide to let the first man accompany the driver (while the others were walking) to the point T_1 and get the first man off. Then, the driver immediately turns back to the point D_2 to come along with the second man to chase the first man and they meet at the point T_2. Then, the second man walks together with the first one to B and the driver comes back to the third one. The process continues to the k man, he would be picked up at T_k and gotten off at D_k to meet the others. Know that n>2, the velocity of all walkers is the same and equal to u. The velocity of the motorbike is v with one person and with two people, it is v^'.
I'm not sure about my answer
 

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  • #2
You need to provide an attempt at a solution before you can get any help, per rules. Why are you not sure about your answer? How did you arrive at your answer?
 
  • #3
My total distance is this equation
 

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  • #4
Do you want us to check it for you? We do that, on occaision, depending on what else is goin' on in our lives. You did not respond to my two questions. Please do.
 
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  • #5
lewando said:
Do you want us to check it for you? We do that, on occaision, depending on what else is goin on in our lives. You did not respond to my two questions. Please do.
Yep, please check it for me. I think it's a difficult one and want to share for everyone. Just that :)
 
  • #6
HP-Physics said:
My total distance is this equation
That doesn't look right to me at all. I would expect to see n as an exponent in the answer.
It is certainly wrong at n=2, but that can be corrected merely by changing one sign in your answer.

Edit: all nonsense... see post #9.

Please post your working.
 
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  • #7
haruspex said:
That doesn't look right to me at all. I would expect to see n as an exponent in the answer.
It is certainly wrong at n=2, but that can be corrected merely by changing one sign in your answer.

Please post your working.
Yes, with n=2 it's quite simple and the original of this exercise. I'm trying to do with n>2. Okie
 
  • #8
I'm really sorry about my English grammar, it is not good
 

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  • #9
HP-Physics said:
I'm really sorry about my English grammar, it is not good
I take it all back. 🤭
My intuition about the form of the answer was based on a wrong view of the question, and I blundered in checking your answer at n=2.
I get the same answer as you do, by a somewhat different route.
 
  • #10
haruspex said:
I take it all back. 🤭
My intuition about the form of the answer was based on a wrong view of the question, and I blundered in checking your answer at n=2.
I get the same answer as you do, by a somewhat different route.
How do you think, about this problem?
 
  • #11
HP-Physics said:
How do you think, about this problem?
Do you mean, how did I approach it?
 
  • #12
Not really, I mean if you have any better solutions
 
  • #13
HP-Physics said:
Not really, I mean if you have any better solutions
Don't know that it is better, still quite messy.
I used y for forward motoring step distance, y-x for reverse motoring step, t for time of one of each.
t = y/v'+(y-x)/v = x/u
L = y + (n-2)x
From which we can find x and y.
Total distance = y + (n-2)(2y-x)
 

1. What is kinematics and why is it important?

Kinematics is the branch of physics that studies the motion of objects without considering the forces that cause the motion. It is important because it helps us understand and describe the motion of objects, which is essential for a wide range of scientific and technological applications.

2. What are the basic concepts of kinematics?

The basic concepts of kinematics include displacement, velocity, acceleration, and time. Displacement is the change in position of an object, velocity is the rate of change of displacement, acceleration is the rate of change of velocity, and time is the duration of the motion.

3. How do I solve kinematics problems?

To solve kinematics problems, you need to first identify the given information, such as initial and final positions, velocities, and accelerations. Then, use the kinematic equations to solve for the unknown variables. It is important to draw a diagram and label all the known and unknown quantities to help visualize the problem.

4. What are the kinematic equations?

The kinematic equations are a set of equations that relate the displacement, velocity, acceleration, and time of an object in motion. They are:
- v = u + at (where v is final velocity, u is initial velocity, a is acceleration, and t is time)
- s = ut + 1/2at2 (where s is displacement)
- v2 = u2 + 2as (where v is final velocity, u is initial velocity, a is acceleration, and s is displacement)

5. What are some common mistakes to avoid when solving kinematics problems?

Some common mistakes to avoid when solving kinematics problems include using the wrong kinematic equation, not converting units correctly, and not considering the direction of motion. It is important to carefully read the problem and identify all the given information before attempting to solve it.

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