Recent content by dura

I had a question regarding a sound with a given Intensity and a given radius (say 0.1m from point source) that travels through a door with dimensions given as well. It also gives a second radius (say 30m from point source) and asks what the acoustic power was at a second radius after traveling...

sorry, my math text writing sucks. The mass should read 3.2x10 (superscript) -12

QUESTION: a small dust mote of mass 3.2x10^-12kg is between two metal plates (one + one -)which can be conected to a 20V power supply. When the power supply is turned on, an electric field of 400 V/m is established. It is observed that the mote starts from rest when the field is turned on...

Regarding the last part of this question, how can I relate the fact taht centripetal force between the moon and Earth is the same as the gravitational force acting between Earth and moon. Isn't this the same thing? The question asks me to explain clearly. I am not sure how to word this?

Thank you... you know, its getting late and I have been doing physics all day. I think my brain has quit!

QUESTION: the mass of the moon is 7.3x10^22 kg and its orbital speed about the Earth is 1024m/s. The distance between the centers of the Earth and moon is 3.844x10^24 m. a) what is the value of the centripetal force acting on the moon? b) the mass ofthe Earth is 5.98x10^24 kg and the...

Thank you Chen for your reply! I still have stupid questions however. I did draw a FBD and see that the sum of all forces must be 0. I am still confused. When I take \Sigma F_y = 0, as FN + (-mg cos 30) = 0... not knowing the normal force or the mass of the object, I am left with gravity and...

Problem reads: A package case of mass m is left 10 m up on a 30 degree ramp overnight where it is at rest. a) what is the minimum value of the static coefficient of friction for this to be ture? Prove in general that the coefficient of static friction is \mu_s = \tan \theta . b) during the...