Forces result from interactions! As discussed in Lesson 2some forces result from contact interactions normal, frictional, tensional, and applied forces are examples of contact forces and other forces are the result of action-at-a-distance interactions gravitational, electrical, and magnetic forces. According to Newton, whenever objects A and B interact with each other, they exert forces upon each other.
How to Solve Force Problems 1. In other cases, it is harder to recognize 2nd Law problems.
You may know forces that are present without having force ever mentioned in the problem, and you may be asked for things like how fast an object moves in a circle or how much of an object is underwater. Draw a Picture When you approach force problems, a free body diagram will allow you to both picture what is happening and directly map the picture into the equation.
All the physics is done in the process of drawing the diagram—only algebra remains after this step. The first thing that you will need to do is to identify what object Newtons third law will be the focus of the diagram—in other words, what system do you need to consider in order to answer the question.
In some cases, you will need to consider several objects as separate systems. In those cases, you will draw free body diagrams and set up equations for each object separately. Once you have identified your system, think about all forces on that system, discard any that are too small to matter.
Only forces acting on the object should be shown, since you are trying to understand what causes the motion of the object. Acceleration is the result not the cause—if you wish to sketch the acceleration, make sure that you do so off to the side and not on the sketch of forces.
Math is always easiest if you pick one axis to be along the direction of acceleration. That way, one component of a will be zero and you will have fewer linked equations. This true no matter what you are asked to find.
If any additional information is needed, it will become apparent as you work through the problem. Think carefully about the direction of each force and include the appropriate sign. Once you have filled your forces into these equations, you have only algebra left and can solve the equations in any way that works.
Understand the Results Once you have completed the problem, look at it again. Does your answer make sense? Did it give the behavior you intuitively expected to find? Can you now do steps that caused you problems earlier? Can you explain in words what is happening?
If you only recognized it as a 2nd Law problem because of the section heading in your text book, identify the information that you would use to recognize a problem like this on the final exam. One of the most common mistakes is to think too hard. Check Definition and Ratio problems to see if you can find a useful example.
It is also possible that your problem is better solved using kinematics description of motion or energy and momentum.
Can you clearly explain to yourself that your problem requires you to relate the cause of motion forces to the effect of those forces acceleration or changing velocity? In that case, think more broadly about what makes a useful example.
Remember, you were given your assignment to practice the problem solving approach, not because the answers to your problems are particularly interesting.In this segment, NBC's Lester Holt looks at Newton's Third Law of Motion and how the conservation of energy is key to keeping a player moving and to .
A person drives a cart, Cart 1, to the right while pushing another cart, Cart 2, that has a massive refrigerator on it. The total mass of Cart 2, cart plus fridge, is . However, the Second Law gives us an exact relationship between force, mass, and acceleration.
It can be expressed as a mathematical equation. Newton's law of gravitation: Newton’s law of gravitation,, statement that any particle of matter in the universe attracts any other with a force varying directly as the product of the masses and inversely as the square of the distance between them.
In symbols, the magnitude of the attractive force F is equal to G (the.
Learn about the fact that forces cause acceleration. Newton's Laws of Motion There was this fellow in England named Sir Isaac Newton.A little bit stuffy, bad hair, but quite an intelligent guy.
He worked on developing calculus and physics at the same time. During his work, he came up with the three basic ideas that are applied to the physics of most motion (NOT modern physics).The ideas have been .