Deviate From The Ideal...

...Gas Law! All real gases deviate to some extent from the ideal behavior described by the Ideal Gas Law equation pV = mRT . For which of the following conditions are the deviations smallest?

(Physics) Minimum Total Mechanical Energy

Consider the following sketch of potential energy for a particle as a function of position. 
There are no dissipative forces or internal sources of energy. What is the minimum total mechanical energy that the particle can have if you know that it has traveled over the entire region of X shown?

 

Note: Even if you don't know, guess! Then learn from the solution for next time!

(Physics) Block Attached to Spring on Incline

A block of mass m is attached to a relaxed spring on an inclined plane. The 
block is allowed to slide down the incline, and comes to rest. The coefficient of kinetic 
friction of the block on the incline is µk. For which definition of the system is the change 
in total energy (after the block is released) zero? 

Arduino Clock (Electronics)

 

Getting up in the morning is hard. After coming across the Chlonos Arduino Clock, you decide to make your own alarm clock...(that speaks to you while flashing awesome looking optics.)

First you get the parts: a speech synthesizer, a speaker, an LED display, a realtime clock, a temperature sensor, a 9V battery, and some AA batteries. 

What does the temperature sensor voltage (V1) and clock voltage (V4) need to be to ensure optimal performance?

Just 13 Floors Away...

Got a fun, "open-ended" engineering riddle or question?
Submit it here, and we'll feature it as a future question!

You're riding the elevator going up to your next meeting, 13 floors above... As you rise, the lights start flickering. Then suddenly, with just a few floors left to go, everything goes black.... and the elevator begins decelerating to a grinding stop. 

                                                                    Tower of Terror Elevator / Jbefig / CC BY 

                                                                    Tower of Terror Elevator / Jbefig / CC BY 

Well, that sucks. But most importantly, what's your normal force on the elevator while it's grinding to a stop?