man0005's physics thread :)

[man0005]

ahhh i see now, so many steps!  hate electricity D:
thanks for all the help so far ^^

i have another one 
A uniform beam of mass 1500 kg is used as a cantilever as shown

P-24m-Q<------------> 36m
-----------------------
I          I
I          I
I          I

The supports are made of wood (compressive strength 3.5 x 10^7, tensile strength 4.0 x 10^7)
and there is a safety factor of 6. What is the minimum cross-sectional area of each support?

[man0005]

can someone please explain to me why the graph for this question shows a negative voltage for this? :S

Edit: actually could someone just explain how the graphs work/how to sketch
i have no idea how to do this one either...

[man0005]

anyone?

[xZero]

As I said, nobody likes electronics For question 7, When the voltage is above or equal to 0.7v, there won't be any output voltage since all the current will flow through the diode (the current will always flow through the smallest resistance path, in this case the resistance is approaching 0, hence the other path will have almost 0 current, this is important so take note of it)

When the voltage is below 0.7v, we can ignore the diode since the resistance is approaching infinity. To sketch the graph, work out the output voltage when input voltage is 0.7v and -10v and it should make a sin/cos curve.

and sorry cant help with q5, don't understand it at all  cant help with the structure question as well, I did relativity instead