Physics GRE Discussion Forums

I noticed when I was doing this problem that the only way to solve this problem in a reasonable amount of time was to take an approximation at an early phase of the calculation, specifically you must let 60/66.6 ~ 1

now once you do that you can quickly solve the problem.

My question is this--- how do I know when to do these time saving tricks--- im guessing you learn mostly by practicing but if someone could point me to some more helpful info on this subject i would be interested

thx

Well, the answers to this problem differ from each other at least by the factor of 2. So unless you did a HUGE mistake, for instance, something like
$$3 \approx 2$$
or worse, you probably came to the right result.

By the way, it is useful to remember that, with a good precision
$$\pi^2 \approx 10; ~ g \approx 10; \sqrt{2} \approx 1.4; \sqrt{3} \approx 1.7$$
and so forth.

physicsworks wrote:Well, the answers to this problem differ from each other at least by the factor of 2. So unless you did a HUGE mistake, for instance, something like
$$3 \approx 2$$
or worse, you probably came to the right result.

By the way, it is useful to remember that, with a good precision
$$\pi^2 \approx 10; ~ g \approx 10; \sqrt{2} \approx 1.4; \sqrt{3} \approx 1.7$$
and so forth.

thx