How Can I Apply Newton's Second Law with Friction in Real-Life Problems?

[gotmilk954]

ok, i need some serious help with Newtons second law. like i kind of understand it, but adding things like friction are giving me real problems. does anyone have any good resources or tips on how to understand/comprehend this?

and i have a prolem:

a man pushes a 15 kg lawnmower at constant speed with a force of 90 N directed along the handle, which is at an angle of 30 degrees to the horizontal. calucalte: (a) the horizontal frictional force on the mower, and (b) the normal force
on the mower.

well i know the acceleration is zero, but don't you need the kinetic friction to find the frictional force?

 

[Mattowander]

I suggest you ask in these forums : https://www.physicsforums.com/forumdisplay.php?f=61

Unless you have a specific homework question

 

[baba89]

Hello,

First of all, don't worry, understanding Newton's Second Law can be challenging for many people. It is important to break down the problem into smaller parts and focus on one aspect at a time. Let me provide some resources and tips that may help you understand this concept better.

1. Watch online videos: There are many educational videos available online that explain Newton's Second Law in a simple and visual way. These videos can help you understand the concept and also provide examples to help you apply it to real-life situations.

2. Practice problems: The more you practice, the better you will understand the concept. Look for practice problems online or in your textbook and try to solve them on your own. If you get stuck, don't hesitate to ask for help from your teacher or classmates.

3. Understand the formula: Newton's Second Law can be written as F=ma, where F is the net force acting on an object, m is the mass of the object, and a is the acceleration of the object. Remember, acceleration is the change in velocity over time.

Now, let's move on to your specific problem. To calculate the frictional force, you need to use the formula Ff=μN, where μ is the coefficient of friction and N is the normal force. The normal force is the force exerted by the surface on the object and is always perpendicular to the surface. In this case, the normal force will be equal to the weight of the lawnmower, which is 15 kg times the acceleration due to gravity (9.8 m/s^2). To find the kinetic friction, you also need to know the coefficient of friction, which can vary depending on the surface and the objects in contact. You can look up the coefficient of friction for a lawnmower on a grass surface and use that in your calculation.

I hope this helps you understand Newton's Second Law better and solve your problem. Remember, practice and breaking down the problem into smaller parts are key to understanding any scientific concept. Good luck!