Chair push Newtons Laws

In summary, a chair with a mass of 13.0 is being pushed with a force of 45.0 directed at an angle of 40.0 below the horizontal on a non-frictionless floor. The normal force can be found using the equation N = mg - Fsin(theta), where theta is the angle of the applied force. The normal force is directed upward and must be equal in magnitude to the downward forces acting on the chair in order to keep it from falling through the floor.
  • #1
CallingAllCars7
3
0
:confused:

Homework Statement



A chair of mass 13.0 is sitting on the horizontal floor; the floor is not frictionless. You push on the chair with a force = 45.0 that is directed at an angle of 40.0 below the horizontal and the chair slides along the floor.




[b]2. Homework Equations [/B]

These were given to me to help.
N= w-F1sin()
Fcos()=ma






The Attempt at a Solution



with the equations given to me by the TA I thought that the answer would be 9.8*13-45sin(), but I keep getting the answer incorrect(my class uses masteringphysics for hw) and I even tried all sorts of other crazy equations.
Please Help, I am on the verge of Physics Failure.:grumpy:
 
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  • #2
cant let that happen. first of all do you know what is menat by a normal force?

The way i think about it is in terms of sum(forces)=m*a If our object of mass m (chair) is not falling thru the floor, there must be an equal and opposite force acting to prevent it. So sum up all the downward forces, subtract any present that might be lifting the chair, and you have normal force, only its directed upward. In this case the angle is below vertical so any "push" adds to the weight. That help at all?

PS: Also add the questions to the problem as they were omitted on the original post.
 
  • #3




It seems like you are on the right track with using Newton's Laws and the given equations. However, there may be a few things you need to consider in order to arrive at the correct answer.

First, make sure you are using the correct units for mass (in kilograms) and force (in Newtons). This may be a common mistake that could lead to incorrect answers.

Secondly, when using the equation N = w - F1sin(theta), make sure you are using the correct angle for the force (in this case, 40 degrees below the horizontal).

Lastly, remember that the force you are applying is not the only force acting on the chair. There is also the force of friction between the chair and the floor. This force will need to be taken into account in your calculations.

Additionally, it may be helpful to draw a free body diagram to better understand the forces acting on the chair and how they relate to each other. This can also help you set up the correct equations to solve for the unknown variables.

Overall, keep in mind that physics can be challenging and it's normal to struggle with certain concepts. Don't be discouraged and keep practicing, as it will help you improve and understand the material better. If you continue to have trouble, don't hesitate to reach out to your TA or professor for additional help.
 

1. What are Newton's Laws of Motion?

Newton's Laws of Motion are a set of three physical laws that describe the behavior of objects in motion. They were developed by Sir Isaac Newton in the 17th century and are considered the foundation of classical mechanics.

2. How do Newton's Laws apply to chair pushing?

Newton's Laws apply to chair pushing in a few ways. The first law, also known as the law of inertia, states that an object at rest will remain at rest unless acted upon by an external force. This means that the chair will not move unless someone pushes it. The second law, also known as the law of acceleration, states that the force applied to an object is directly proportional to its mass and acceleration. This means that the heavier the chair and the more force applied, the faster it will accelerate. The third law, also known as the law of action and reaction, states that for every action, there is an equal and opposite reaction. This means that when someone pushes the chair, the chair will push back with an equal force.

3. How can I calculate the force needed to push a chair?

The force needed to push a chair can be calculated using Newton's second law of motion. The formula is force = mass x acceleration. First, determine the mass of the chair. Then, estimate the acceleration needed to move the chair (e.g. how fast you want it to move). Plug these values into the formula to calculate the force needed.

4. Can a chair ever be pushed with a constant speed?

Yes, according to Newton's first law of motion, an object in motion will remain in motion with a constant speed and direction unless acted upon by an external force. This means that if you push a chair with a constant force, it will continue to move at a constant speed until you stop pushing or another force acts on it.

5. What are some real-life applications of Newton's Laws?

Newton's Laws have many real-life applications, including understanding how objects move in space, designing vehicles and machinery, and even sports activities like throwing a ball or riding a bike. In the case of chair pushing, these laws also apply to understanding how objects move and interact with each other in everyday situations.

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