Newton's law trick? question

In summary, the problem involves a 40 kg girl and a 50 kg boy on a frozen lake, 10 m apart. The girl exerts a horizontal 5.0 N force on the boy using a rope, causing the boy to accelerate towards her. The magnitude of the girl's acceleration can be calculated using Newton's third law, which states that for every action, there is an equal and opposite reaction. Therefore, the force on the girl would also be 5.0 N and her acceleration can be calculated using the equation F=ma.
  • #1
iamtrojan3
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Newton's law "trick?" question

Homework Statement


A 40 kg girl and a 50 kg boy are on the surface of a frozen lake, 10 m apart. Using a rope, the girl exerts a horizontal 5.0 N force on the boy, pulling him toward her. Calculate the magnitude of the girl's acceleration.

Homework Equations



F=ma

The Attempt at a Solution


i don't really know where the distance from the problem comes in and its not as simple as it looks... apparently.
I thought about how if the girl pulled the rope with 5N then the only mass that's moving is the boy, but that wasn't right. Adding the weights together didn't work either.
THe hint i got was "Newton's 3rd law"
how will that apply to this problem? i understand the concept of the 3rd law.

Thanks!
 
Last edited:
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  • #2


iamtrojan3 said:
i understand the concept of the 3rd law.

Then what would be the force on the girl?
 
  • #3


Yea... misread question >.<
i hate when that happens
thanks.
 

1. What is Newton's law trick?

Newton's law trick is a scientific demonstration that illustrates Newton's third law of motion, which states that for every action, there is an equal and opposite reaction. It involves balancing a pencil on its tip, then flicking it with your finger so that it spins in the air and lands back on its tip.

2. How does Newton's law trick work?

When the pencil is balanced on its tip, the force of gravity is acting on it, causing it to stay in place. When you flick the pencil, your finger exerts a force on it, causing it to spin. According to Newton's third law, the pencil exerts an equal and opposite force on your finger, which allows it to spin and land back on its tip.

3. What materials are needed for Newton's law trick?

All you need for this trick is a pencil and a flat surface to balance it on, such as a table or desk. The pencil should be sharpened and have a flat tip for better balance.

4. Is Newton's law trick only for demonstration purposes?

No, Newton's law trick is not just for demonstration purposes. It is a real-life example of Newton's third law of motion, which is a fundamental principle in physics that applies to all objects and interactions in the universe.

5. What other concepts can I learn from Newton's law trick?

In addition to understanding Newton's third law of motion, the trick can also demonstrate concepts such as inertia, center of mass, and conservation of angular momentum. It can also be used to explain other everyday phenomena, such as the spin of a football or the flight of a frisbee.

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