# How Far Can a Person Stand on a Plank Without It Tipping?

• gcombina
In summary, the problem involves a horizontal plank weighing 100 N and an 800-N person standing on it. The plank is supported by two points 1.0 m from each end. The question is asking for the maximum distance from one end that the person can stand without causing the plank to tip. Using the formula F x Dist, we can determine that the length on the other side would be 90 meters, which equates to 90N. To balance the plank, we must consider the weight of the person (800 * (1-X)) and the weight of the rest of the plank (10 N * 0.5 m).
gcombina

## Homework Statement

A horizontal, 10-m plank weighs 100 N. It rests on two supports that are placed 1.0 m from each end as shown in the figure. How close to one end can an 800-N person stand without causing the plank to tip?

## The Attempt at a Solution

I know the person weighs 800 and there is X distance

so I have 800N from the weight of the person plus 10 N from the weight of the plank on the right side of the fulcrum

800X + 10 N = 90 N (the weight of the rest of the plank)

#### Attachments

• Question 26 (ch 7-9 test).png
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Isn't the formula F x Dist so that for this case (800 + 10) * X and the length on the other side would be?

jedishrfu said:
Isn't the formula F x Dist so that for this case (800 + 10) * X and the length on the other side would be?

the length of the other side would be 90 meters which equates to 90N

Not good.
On the left we have 90 N * 4.5 m (as we had in October...)
On the right we have
from the person: 800 * (1-X) if X is the distance from the end of the plank
from the plank: 10 N * 0.5 m (Haru's "the rest of the plank")

Now balance the lot and you're done.

Good luck with the exam :)

To solve this problem, we need to use the principle of moments. This principle states that for an object to be in equilibrium, the sum of the clockwise moments must be equal to the sum of the counterclockwise moments. In this case, the clockwise moments are caused by the weight of the person and the plank on the right side of the fulcrum, while the counterclockwise moments are caused by the weight of the plank on the left side of the fulcrum.

Using this principle, we can set up the following equation:

(800N * x) + (100N * 1m) = (100N * 9m)

Where x is the distance from the left end of the plank to the person's position. We know that the weight of the person and the plank on the right side must be equal to the weight of the rest of the plank on the left side in order for the plank to be in equilibrium.

Solving for x, we get:

800x + 100 = 900

800x = 800

x = 1m

Therefore, the person can stand up to 1m from the left end of the plank without causing it to tip. Any closer, and the clockwise moments would be greater than the counterclockwise moments, causing the plank to tip.

## 1. What is the Plank Question?

The Plank Question is a thought experiment proposed by German physicist Max Plank in the early 20th century. It asks whether energy is emitted or absorbed in discrete packets or "quanta" rather than continuously. This concept led to the development of quantum mechanics and revolutionized our understanding of the behavior of matter and energy.

## 2. How does the Plank Question relate to tomorrow's final?

The Plank Question is often included in physics curriculum and may be covered in your final exam. It is a fundamental concept in understanding the behavior of matter and energy, so it is important to have a solid understanding of it for your final.

## 3. Why is the Plank Question significant?

The Plank Question is significant because it challenged the traditional understanding of the behavior of matter and energy. It led to the development of quantum mechanics, which has had a major impact on modern physics and technology. It also highlights the important role of thought experiments in scientific discovery.

## 4. How can I prepare for a question about the Plank Question on my final?

To prepare for a question about the Plank Question on your final, make sure you understand the concept and its implications. Review any relevant lecture notes, textbook chapters, and practice problems. You can also try to apply the concept to real-world examples to solidify your understanding.

## 5. Can you provide an example of how the Plank Question has been applied in real life?

One example of the application of the Plank Question is in the development of modern technology, such as LED lights and solar panels. These technologies rely on the understanding of quantum mechanics and the behavior of energy in discrete packets. Without the Plank Question, we may not have been able to develop these technologies that have greatly impacted our daily lives.

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