Posts

Showing posts from April, 2007

Student Final Report Concern

My Student Final Project Report is terribly written, badly structured and formatted. This maybe due to the tendency of them doing a group project and handing in one report per group. See the video for details...

Falling down handphone. Why is it broken falling from high story building even though the force is the same.

Image
A student ask me today, about the effect of distance to the force of an object falling down. In this case it's a about a hand phone, falling down. The question is wouldn't the force be the same, if it's 1 story vs 10 story building? But why if it's higher it will break? I search for force vs momentum and I found out this web page. Nice explanation by 3 physics instructor of some sorts. How is force related to momentum? or the link http://www.physlink.com/Education/AskExperts/ae462.cfm The answer for my student question is that when the handphoen meet the floor at a very short time, the force will be very high due to the short time that the handphoen stopped. If it's a soft surface the handphone will have more time, so the force will be much lower. Here is the most related answer. Newton's 2nd Law tells us that force = mass x acceleration ( F = ma ). Since acceleration is just how velocity changes over time, we can write this as F = m * v/t Multiply both sides by