Problem 1.2. KINEMATICS | Learning to solve physics problems from scratch
If you've decided to learn how to solve physics problems from scratch, you've come to the right place. On my channel, I'll be solving a wide variety of problems in kinematics, dynamics, and other areas of physics, with a very simple and accessible explanation of the solution algorithm. I think almost anyone will understand it.
On this channel, I plan to post solutions, tips, and recommendations for schoolchildren and students who want to learn how to solve physics problems. So, if you have any questions about my problems or would like clarification on anything, please ask in the comments. I'll record videos answering your questions if needed. ▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
► Problem 1.2
The car traveled the first half of its journey at a speed of V1 = 80 km/h, and the second half at a speed of V2 = 40 km/h. What is the average speed Vav of the car?
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► DOWNLOAD A PHOTO OF MY PHYSICS NOTEBOOK:
(in the "Physics" section)
https://www.toe1.ru
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It's important to remember that physics problems, by their very nature, are something that surrounds us. These processes, actions, and mechanisms we encounter when solving a problem are all part of the world around us. When approaching a new problem, even the simplest one, try to recognize the phenomenon, visualize it (as a picture), discuss its process (if possible), and only then begin searching for an answer to the problem question.
You can formulate the problem as you imagined it:
a brief statement of the conditions, which should reflect not only the given numerical values but also all additional conditions that follow from the problem text (although this is not always obvious, but arises as you solve it).
Illustrating the problem with a drawing: create a drawing for the problem that displays the situation described in the problem, include all the given conditions, and formulate the problem question.
A drawing is especially necessary if the equations used are given in vector form. In this case, you need to draw a coordinate system relative to which the vector equation should be written in projections. In most cases, a drawing greatly facilitates the process of solving any problem, not just in physics. A drawing is also necessary if the body is moving or at an angle.
You need to check that all the given quantities in the problem are in the same system of units (SI, CGS, or others). If the quantities are given in different systems, they should be expressed in units of the system you are using for the solution. The SI system is preferred, but not always.
So, the problem statement is formulated; now you can begin solving it.
Consider the physical content of the problem, determine which section it belongs to, and what laws should be used. Problems can be combined; their solution requires the use of laws from several branches of physics.
Next, you should write down the formulas corresponding to the laws used in the problem. Don't immediately look for the unknown quantity; you need to check that all the parameters in the formula are known. If the number of unknowns is greater than the number of equations, you should add equations that follow from the statement and the drawing. General principle: the number of unknowns equals the number of formulas. Then all that remains is to solve the system of equations, that is, reduce the problem from a physical to a mathematical one. A common mistake: not fully understanding the meaning of the parameters in a formula. Schoolchildren are quite capable of solving a physics problem, but often get confused by their notation.
-Problem solutions should usually be presented in general terms, that is, using letter notations.
-Having obtained a general solution, you need to check the dimensions of the resulting quantity. To do this, substitute the dimensions of the quantities involved into the formula, not the numbers. After checking the formula for dimensions, you should substitute the numerical values of the quantities involved and perform the calculation.
-Next, you need to analyze and formulate an answer. If the question was "how has..." changed, you should also indicate the direction of the change (increased, decreased, slowed, etc.).
Start solving problems daily, and after a while, you'll feel that you can solve each subsequent problem faster and with less effort. You'll learn to "see" them from the inside, even without drawings. But this skill is developed only through regular practice. The ability to quickly solve problems will come in handy not only when passing exams, but also when studying at university.
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✅ Thank the channel's author:
4276510010822044 (Sberbank)
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► MAIN CHANNEL (Electrical Engineering):
/ @toeravilov
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