Having a hard time learning Newton's 2nd law

[Sixty4Fairlane]

Homework Statement

Newton's 2nd law

Relevant Equations

F = ma
Etc

I'm taking college physics without calculus this semester and it's been quite the challenge to say the least. We recently covered free body diagrams and while I understand the different vectors in the FBD, making calculations is killing me. Specifically Newton's 2nd law.


The problems range from:

• Calculating acceleration on incline (given force, mass, and angle above horizontal).

• Calculating the weight of a person on a scale in an elevator accelerating downward.

• Calculating coefficient of friction (given a constant velocity and angle above horizontal).

• Calculating the force needed to slide an object across a surface given the two coefficients of friction.

And similar scenarios.

What I'm stuck on is the fact that there are so many different formulas for different scenarios. My foundation of math skills isn't the greatest. The lecture material in my course is not good and doesn't follow the assignment questions and I don't know how to learn to do all this so quickly. I've tried talking to my professor, but there's only so much she can do. I've used several channels on YouTube, but its overwhelming to see the amount of steps/work to complete one problem and then remember it without your notes. I have looked on Chegg to see the steps needed to solve, but without a clear explanation, I'm still lost. I understand you have to work at it, and I am, but I was wondering if you guys had any advice that helped you when you were learning this stuff. Thanks.

 

[BvU]

Hello @Sixty4Fairlane

​

The lecture material in my course is not good

I sympathize. Does it say where the stuff comes from or if it's based on a particular textbook?
Does your school have a library where you can browse textbooks to find one that suits you better ?

Alternatively there is a PF textbooks forum

At this stage the internet is overwhelming and youtube a waste of time -- as you found out already.

there's only so much she can do

Surely she can do something !?!?

##\ ##

 

[strangerep]

I was wondering if you guys had any advice that helped you when you were learning this stuff.

Work through lots of exercises.

If you're having trouble with any particular exercise, well, that's what the PF homework forums are for, provided you use the HW template conscientiously. I.e., give a complete statement of problem as originally worded, write out potentially relevant equations (even if you're not sure how to use them), show your initial, partial, attempt at a solution (even if it's just your initial thoughts), etc.

(Also, learn how to use latex for math formulas on the forum as soon as you can.)

 

[PeroK]

Homework Statement: Newton's 2nd law
Relevant Equations: F = ma
Etc

I'm taking college physics without calculus this semester and it's been quite the challenge to say the least. We recently covered free body diagrams and while I understand the different vectors in the FBD, making calculations is killing me. Specifically Newton's 2nd law.


The problems range from:

• Calculating acceleration on incline (given force, mass, and angle above horizontal).

• Calculating the weight of a person on a scale in an elevator accelerating downward.

• Calculating coefficient of friction (given a constant velocity and angle above horizontal).

• Calculating the force needed to slide an object across a surface given the two coefficients of friction.

And similar scenarios.

What I'm stuck on is the fact that there are so many different formulas for different scenarios. My foundation of math skills isn't the greatest. The lecture material in my course is not good and doesn't follow the assignment questions and I don't know how to learn to do all this so quickly. I've tried talking to my professor, but there's only so much she can do. I've used several channels on YouTube, but its overwhelming to see the amount of steps/work to complete one problem and then remember it without your notes. I have looked on Chegg to see the steps needed to solve, but without a clear explanation, I'm still lost. I understand you have to work at it, and I am, but I was wondering if you guys had any advice that helped you when you were learning this stuff. Thanks.

I assume from this post that you don't actually understand these problems, but see the solution as a list of random steps and random formulas.

The normal advice is to do lots and lots of problems until things sink in and you gain some understanding through memorisation and rote learning.

Personally, I would try to focus on what precisely you do not understand. For example, if we place a block on an inclined plane it can either stay where it is or slide down. Can you explain those two cases to yourself, first descriptive and then in formulas?

 

[Chestermiller]

I'm surprised that, with your mathematical experience, you are having trouble. The problems on your list all involve resolving vectors into orthogonal components and using the condition that, as reckoned from an inertial (laboratory frame of reference), the vector sum of the forces on a body is equal to its mass times its acceleration vector.

 

[MatinSAR]

The lecture material in my course is not good and doesn't follow the assignment questions and I don't know how to learn to do all this so quickly. I've tried talking to my professor, but there's only so much she can do. I've used several channels on YouTube

I had this problem with Newton's laws too. The reason for me was that I didn't solve any problem and I was just reading about laws and ...
Another mistake that I made was that I used many many sources for learning. Different books,classes,YouTube channels. In my opinion this is wrong when you want to learn sth new.

but its overwhelming to see the amount of steps/work to complete one problem and then remember it without your notes. I have looked on Chegg to see the steps needed to solve, but without a clear explanation, I'm still lost.

Why don't start with questions that doesn't need lots of steps to solve? Then If you successfully answer them you find out you know something about Newton's law so you try to solve harder problems.

I understand you have to work at it, and I am, but I was wondering if you guys had any advice that helped you when you were learning this stuff. Thanks.

I've learned this way:
1. Read about N's laws in good books.
2. Try to solve or read the answered examples that are provided in the book. These examples help students understand better.
3. Solve easier questions. When I am solving a question I give my self a reason for everything that I'm writing. This way I know that I've learned the topic and I'm not using formulas or laws randomly.
4. I try to solve harder questions and If I fail I ask someone for help. You can ask questions at this forum you will receive help from experts.

I'm not sure what your course is so Idk what books are good for you ...
I've read about Newton's laws in these books:

• Fundamentals of Physics(Textbook by David Halliday, Jearl Walker, and Robert Resnick).
• Classical dynamics of particles and systems(Book by Stephen Thornton).