Minimum force needed to move block

In summary, the conversation discusses the concept of overcoming friction in order to put a block in motion. While the physics professor believes that a force of 1 N is needed, the speaker argues that a force greater than 1 N is necessary to overcome static friction and create a net force. The conclusion is that the force of friction must be overcome in order to put a block in motion.
  • #1
Fizic
23
0
This isn't a specific problem, but it is a concept that appears in several problems.

I'll give an example problem that should make clear what I mean.

A block rests on a horizontal surface. Ffric≤1 N. What force (applied horizontally) is needed to move the block?

My physics professor says 1 N, but I say >1 N, because if you apply a force of exactly 1 N, it will exactly cancel out with friction and there will be no net force. If it is any greater than 1 N, static friction will be overcome and hence a net force will be present.

So my question is, to put a block in motion, does the force of friction have to be cancelled(Fapp=Ffric), or overcome(Fapp>Ffric)?
 
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  • #2
The answer is that the force of friction must be overcome. In order to put a block in motion, the applied force must be greater than the friction force. This means that the applied force must be greater than 1 N in the example problem given.
 

1. What is the minimum force needed to move a block?

The minimum force needed to move a block depends on several factors such as the weight and surface of the block, the type of surface it is resting on, and the force of friction. It is typically calculated using the formula F = μN, where F is the force required, μ is the coefficient of friction, and N is the normal force.

2. How does the weight of the block affect the minimum force needed to move it?

The weight of the block directly affects the minimum force needed to move it. The heavier the block, the more force will be required to overcome its inertia and move it. However, the weight alone does not determine the minimum force as it also depends on other factors such as friction.

3. Do different surfaces require different minimum forces to move a block?

Yes, different surfaces can have different coefficients of friction, which affects the minimum force needed to move a block. For example, a block on a rough surface will require more force to move compared to the same block on a smooth surface.

4. How can the minimum force needed to move a block be reduced?

The minimum force needed to move a block can be reduced by decreasing the coefficient of friction, increasing the surface area of the block, or using a lubricant. Additionally, applying the force at an angle rather than directly upwards can also help reduce the required force.

5. Can the minimum force needed to move a block change over time?

Yes, the minimum force needed to move a block can change over time due to factors such as wear and tear of the block and surface, changes in temperature and humidity, and the addition or removal of any lubricants. It is important to regularly check and adjust the minimum force needed to move a block to ensure safety and efficiency.

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