# Studying Ideal time spent on 1 question -- need some advice

1. Jul 19, 2016

### barcodeIIIII

I am an undergraduate student (moving to last year this September). I found out that on my third year, I needed much more time to work on assignments and exam questions compared to 2nd year. I think I am kind of slow and a little bit worried in the last year that things might get out of control.

So my question is how long does it take for you guys to solve a question like this for example ?
(Griffiths, Introduction to Electrodynamics 4th ed, page 147, example 3.9)
A specified charge density $$\sigma_o(\theta)$$ is glued over the surface of a spherical shell of radius R. Find the resulting potential inside and outside the sphere.

It took me 27 minutes to complete the rough work (without looking at solutions& no interruption )and i need 4-5 minutes to present it "nicely" on a new piece of paper.. some assignment questions will take me hours or days.

In short, how long does it take for you guys to solve a question of average difficulty (your own standard)? any advice?

2. Jul 19, 2016

### Incand

I think this is perfectly normal and nothing to worry about (You may even be solving them faster than average). I rarely manage to do a question in less than 30 min. If one looks at the solution of that question it's actually quite long so 30 min isn't a long time at all.
The exercises I learn the most from I often spent an or several days on and often solving them in several different ways (In your example, you could do the integration method as well!).

Do you feel you have problem keeping up with the homework? Maybe you could select the exercises you do more carefully (If you already know exactly how to solve something maybe you don't need to spend time on that exercise) or perhaps you need to put more time towards studying.

3. Jul 19, 2016

### barcodeIIIII

Yes, I do have problems with submitting assignment before deadlines(specially in QM). Usually I will take 4 courses and each course has assignment every 2 weeks, each assignment is about 5 to 8 questions long, I also have pre labs and lab reports due as well. I think this is quite common among physics majors?
Except for assignments, I don't do super hard ones (those i dont have any clue at all). My strategy is going through as many problems as possible so that I can get familiar with the topics. I am afraid if I spent so much time on a question than I don't have time for other stuff.
how many hours per day do you spend on physics? can you please tell me more specifically about how much time you spend on assignments, reading texts..etc?

4. Jul 19, 2016

### gleem

I don't think there is a way of quantifying a priori an average difficulty for problems. There is no benchmark time for doing homework and if there was it would probably vary according to the subject. If you must, I think the best indicator is comparing your performance to you class mates. Ask some of them how long it took them to do some specific problem that you thought took too long. Ask your professor if it is particularly challenging or should it take so and so time to complete . They usually select problems sets that are doable in the allocated time but their may be exceptions for instance the professor may be trying to challenge his students. Sometimes the combination of courses results in a "perfect storm" for getting your homework done. That happens, obviously professors do not coordinate their assignments so you can have reasonable semesters and tough ones.

Anyway budget your time according to your priorities and needs. Don't spend time just staring at a problem. I'm a firm believer in the ability of the mind to work on problems "in the background " so to speak. Read the problem carefully and enough so that you know and understand it with out looking at it, then do something else. Periodically go back to the problem and actively work on it for a while. Repeat as necessary. You may not solve all your problems this way but it may free up time for your other work.

5. Jul 20, 2016

### Incand

It sounds like you have more assignments than I do. I'm assuming 4 courses is the normal course load? I have about the same number of assignments a course but we only have 2-3 courses at a time (Which seem to be more common in Europe, where I'm from). We do however have lots of recommended exercises in addition to this which isn't graded but is needed as preparation for assignments and exams.

I also spend the majority of my study time doing problems. I find if you are always prepared for lectures in advance having already read through the material the lectures reinforces that and you end up needing less time reading through the material and can spend it on problem solving. So in an average week I may spend maybe only 1-2 hours reading through the materials and making minimal notes (writing down the most important formulas or concepts)
I then usually have lectures/labs for another 10 hours. The rest of the time, 20-30hours a week I spend doing problems using the course literature as a reference when problem solving. The exception being when there lab reports to be done, they usually tend to eat up the entire week.

The only real advice I can give you is to always start ahead. I tend to try to be always be at least a week before schedule. That way when you slip behind you have that extra time and if you for some reason can't study for a week (getting sick etc.) you have time to compensate. You also save a lot of time doing it in that order, using the lectures more as a reinforcement than an introduction.

I also agree with @gleem that there's no point staring at a problem. Work for it for a while and if you don't make any progress move on to the next problem but be sure to go back to the problem the next day or a few days later. It's surprising how often the solution comes to you when doing other things.