Physics - Half Life Question Check!!!
An ancient rock is found to contain 40Ar gas, indicating that 77% of the 40K in the rock has decayed since the rock solidified. Any argon would have boiled out of liquid rock. How long ago did the rock solidify? The half-life of 40K is 1.25 billion years. A) 2.6 billion years ...
April 28, 2015
Physics - Vision and Optical Instruments
A camera with a 100 mm focal length lens is to be designed to focus on objects from 75 cm to 20 cm. How far must the lens move as the focus is adjusted from infinity to 75 cm? Thank you!
April 24, 2015
Physics- Solenoid Questions
1) A technician has been given wire that can safely carry 5 A. She has been instructed to construct a solenoid that will have a magnetic field of 0.06 T at its center. After completing some tests of the wire, the technician finds that the tightest safe winding possible with ...
April 1, 2015
5th grade math
John picked 30 bags of apples on monday and sold them at his fruit stand for $3.45 each. The following week he picked and sold 6 more. How much money did John earn the 1 st week? 3.45x30=103.50 How much money did he earn in the second week? 3.45x36=124.20 How much did John ...
November 4, 2014
A mathematical model for concentration of administered cortisone in humans over a 24-hour period uses the function C= [(D x a) / V(a-b)] (e^(-bt)-e^(-at) where C is the concentration, D is the dose given at time t=0, V is the volume of distribution (volume divided by ...
February 13, 2014
A rectangular field is to have an area of 500 sq m. a) write the perimeter, P, of the field as a function of the width, w. b) find the domain of the function in part a. c) use a graphing calculator to sketch the graph of the function in part a. d) describe what the graph found...
January 28, 2014
There are 6 red cards not 16 ( only face cards: 2 kings 2 queens and 2 jacks) and 16 black. 22 in total. a) (6/22)*(5/21)*(4/20)*(3/19) b) (16/22)*(15/21)*(6/20)*(5/19) c) 1-((16/22)*(15/21)*(14/20)*(13/19)) d)(16/22)*(15/21)*(14/20)*(13/19))
December 12, 2010
First you find the volume of the whole ball, then the volume of the round hole inside, then, you subtract the hole's volume from the whole ball's volume, leaving you with the volume of the resulting solid.
February 12, 2008
a solution is made by diluting 175 mL of 0.238 M aluminum nitrate, Al(NO3)3, solution with water to a final vlume of 5.00x 10^2 mL.calculate the following. a. the molarity of aluminum nitrate, aluminum ion, and nitrate ion in the diluted solution B. the number of moles of ...
February 20, 2007