# A theoretical question about forces

• freexd
In summary, when a person lying on a bed is hit by a knee on the edge of the bed, the force created results in a fast head movement towards the direction of impact. However, if the knee were to hit the head directly, the force would not be the same as the headboard would move towards the head and exert a force in the opposite direction. Additionally, if the bed was like a clean table with minimal friction, the force on the head would be close to zero. The force created also depends on the mass and acceleration, so the force would be different if the knee hit the head directly compared to hitting the edge of the bed.
freexd
Hello,

Imagine the following scenario: a person is lying in bed, straight on the back. A second person passes the bed and accidently hits the edge with it's knee. The created force results in a fast head movement of the person on the bed, towards the direction where the impact was.

Is it correct that the force would have been the same high, when the knee hit the head directly?

freexd said:
The created force results in a fast head movement of the person on the bed, towards the direction where the impact was.

I'm assuming there's a headboard, and in such a case it is the headboard that moves towards the person's head. This exerts a force on the head opposite of the direction of impact.

No, it' not correct. Supposing the bed was like a clean table with some kind of oil to eliminate the friction between the body on it and the bed the force on the head is going to be close to zero or zero (idealy).

freexd said:
Is it correct that the force would have been the same high, when the knee hit the head directly?

No. Consider the trick where you pull a table cloth from under a plate. The plate does not accelerate as quickly as the cloth. The forces could be very different.

F=ma, in the two cases the mass is different, the force is the same, so you would get a different acceleration.

## 1. What is a theoretical question about forces?

A theoretical question about forces is a question that seeks to understand the fundamental principles and concepts behind the behavior of forces in the physical world.

## 2. Why is it important to ask theoretical questions about forces?

Asking theoretical questions about forces helps us to better understand the underlying principles and mechanisms that govern the behavior of forces, which can then be applied to real-world situations and help us make predictions and advancements in science and technology.

## 3. How do theoretical questions about forces differ from practical questions?

Theoretical questions about forces focus on understanding the fundamental principles and concepts, while practical questions are concerned with applying these principles to real-world situations and solving specific problems.

## 4. What are some examples of theoretical questions about forces?

Some examples of theoretical questions about forces include "What is the relationship between force and acceleration?", "How do different forces interact with each other?", and "What factors affect the magnitude and direction of a force?"

Theoretical questions about forces can be answered through experimentation, mathematical equations, and theoretical models. Scientists also use existing theories and principles to make predictions and test their validity through further experimentation.

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