Confirm My Answers: Solving the Sled Problem

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In summary, the conversation is about a person working on problems from an old text with errors in the answer key. They have solved a problem involving two girls on a sled and are looking for confirmation on their answers. The person's answers are (a) 0.15 m/s (b) 0 m/s (c) 0.18 m, while the book's answers are (a) 1/6 m/s (b) 0 (c) 6/31m. The person explains their method of using the principle of conservation of momentum to solve the problem and apologizes for not sharing it earlier. The others in the conversation confirm that the person's answers look correct.
  • #1
LD_90
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I'm doing some problems from an old text that seems to be plagued with errors in the answer key. I think my method is correct, but if someone could confirm my answers to this problem, I'd very much appreciative.

Two girls sit on opposite ends of a sled 6.0 m long initially at rest on frictionless ice. Each girl has a mass of 50 k; the sled's mass is 30 kg. The girl at one end throws a 4.0 kg object to the other girl so that the obect travels horizontally at 5.0 m/s relative to the ice. What is the sled's speed (a) before the second girl catches the object? (b) After she catches the object? (c) Over what distance does the sled move while the object is in flight?

My answers (a) 0.15 m/s (b) 0 m/s (c) 0.18 m

The books answers (a) 1/6 m/s (b) 0 (c) 6/31m
 
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  • #2
How did you arrive at your answers?
 
Last edited:
  • #3
LD_90 said:
I'm doing some problems from an old text that seems to be plagued with errors in the answer key. I think my method is correct, but if someone could confirm my answers to this problem, I'd very much appreciative.
We obviously can't comment on your method, since you didn't share it. In the future, even when you just need an answer confirmation, please show us how you did the problem. After all, you took the trouble to type in the problems...a couple more lines won't kill you. :smile: (No need for all the gory details necessarily; just an indication of the principles you applied is often enough.)

And, yes, your answers look good to me.
 
  • #4
Thanks guys. Sorry about not posting my method. I'll give more complete posts in the future and try to learn to LATEX. Well for the problem I assumed an isolated system and used the fact that the total momentum of an isolated system is constant. In this case [tex]p_{1}[/tex] + [tex]p_{2}[/tex]=0
Thanks again
 

1. What is the "Sled Problem"?

The "Sled Problem" is a hypothetical physics problem that involves determining the minimum amount of force needed to pull a sled up a frictionless slope at a constant speed. It is often used as a teaching tool to demonstrate concepts such as work, energy, and force.

2. How do you solve the "Sled Problem"?

The "Sled Problem" can be solved using basic physics principles, such as the work-energy theorem and the concept of mechanical advantage. First, calculate the work required to pull the sled up the slope at a constant speed. Then, determine the minimum force needed to produce that amount of work. Finally, use the concept of mechanical advantage to determine the optimal angle and length of the rope necessary to achieve the minimum force.

3. What factors affect the solution to the "Sled Problem"?

The solution to the "Sled Problem" is affected by several factors, including the mass of the sled, the angle and length of the rope, and the slope of the hill. Additionally, the presence of friction and other external forces can also impact the solution.

4. Are there real-world applications for the "Sled Problem"?

While the "Sled Problem" is often used as a theoretical exercise, it does have real-world applications. For example, it can be used to calculate the minimum force needed to pull a heavy object up a ramp or hill, or to determine the optimal angle and length of a pulley system for lifting objects.

5. What are some tips for solving the "Sled Problem"?

Some tips for solving the "Sled Problem" include breaking the problem down into smaller, more manageable steps, understanding and applying the relevant physics principles, and double-checking your calculations for accuracy. It can also be helpful to draw diagrams or use visual aids to better understand the problem. Practice and patience are also key to successfully solving the "Sled Problem".

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