Understanding the 3rd Law of Motion: Solving a Common Homework Problem

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In summary, the conversation discusses how a person can move a box by pulling on a rope tied to it, even though the box pulls back with equal force. It is explained that the person is able to move due to their greater mass, which allows them to exert more force and overcome the opposite force of the box. It is also mentioned that the acceleration of the person and the box plays a role in their movement, as the person's greater mass causes them to accelerate less and the box to accelerate more.
  • #1
harp AP 2010
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Homework Statement


If I pull forward on a rope tied to a box, and the box pulls back equally, how do we move at all?

Homework Equations


I think I'm over thinking this, but if my actions have equal and opposite reactions how does anything happen?

The Attempt at a Solution

 
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  • #2
well, you move because of your mass, since it is greater than the box the box moves..

3rd law says F12 = -F21

and F= ma

so you see that the more mass you have the more force you exert, overwhelming the opposite force of the box

edit: hmm..i think I'm wrong i think it's because of the acceleration, since a = F / m , the more mass you have the less you accelerate, so the box accelerates more and it moves..but I'm not an expert on this..
 
  • #3
You manage to move the box by digging in your feet with more resistance than the box can muster from its friction with the ground. Imagine doing this on a frictionless surface (ice rink, say). You would just close the distance between you and the box unless you turn your skates round to obtain purchase on the ice.
 

1. What is the 3rd Law of Motion?

The 3rd Law of Motion, also known as Newton's Third Law, states that for every action, there is an equal and opposite reaction. This means that when an object exerts a force on another object, the second object will exert an equal and opposite force back on the first object.

2. How does the 3rd Law of Motion apply to solving homework problems?

The 3rd Law of Motion can be applied to solving homework problems by using it to determine the forces acting on an object and their directions. This can help in calculating the acceleration and movement of the object, and ultimately solving the problem.

3. Can you provide an example of using the 3rd Law of Motion to solve a homework problem?

Sure, let's say a person is pushing a heavy box across a floor. According to the 3rd Law of Motion, the person exerts a force on the box, and the box exerts an equal and opposite force on the person. By knowing the magnitude and direction of these forces, we can calculate the acceleration of the box and how far it will move.

4. What is the importance of understanding the 3rd Law of Motion?

Understanding the 3rd Law of Motion is important because it is a fundamental law of physics that helps explain the behavior of objects in motion. It also allows us to accurately predict and calculate the movement of objects, which is essential in solving many scientific and engineering problems.

5. How can I improve my understanding of the 3rd Law of Motion?

To improve your understanding of the 3rd Law of Motion, you can practice solving different homework problems and applying the law to real-life situations. You can also read textbooks, watch educational videos, and seek help from a teacher or tutor if needed. Hands-on experiments and demonstrations can also help solidify your understanding of the law.

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