Using Ampere's Law, the magnetic field produced inside this solenoid is given by
B = uo N I / h
where uo is the vacuum permeability, N is the number of turns in the solenoid and h is the length of the solenoid. Earth's magnetic field is around 50 microteslas in North America thus the current needed in the solenoid is
I = B h / (uo N) = (50 E-6 ) (4) / ((4 pi E-7)(6000) ) = 0.026 A
I = 26 mA
So you need a current of around 26 mA.
        
             
        
        
        
Answer : 413.44N 
Here it is given that an elevator is moving down with an acceleration of 3.36 m/s² . And we are interested in finding out the apparent weight of a 64.2 kg man . For the diagram refer to the attachment . 
- From the elevator's frame ( non inertial frame of reference) , we would have to think of a pseudo force. 
- The direction of this force is opposite to the direction of acceleration the frame and its magnitude is equal to the product of mass of the concerned body with the acceleration of the frame . 
- When a elevator accelerates down , the weight recorded is less than the actual weight .
From the Free body diagram ,
 
 
 
 
- Mass of the man = 64.2 kg
 
 
 
 
 
 
 
        
             
        
        
        
Hi!
The correct answer would be: the width of I-bands
The sacromere is the smallest contractile unit of striated muscles. These units comprise of filaments (fibrous proteins) that, upon muscle contraction or relaxation, slide past each other. The sacromere consists of thick filaments (myosin) and thin filaments (actin). 
<em>Refer to the attached picture to clearly see the structure of a sacromere.</em>
<u>When a sacromere contracts, a series of changes take place which include:</u>
<em>- Shortening of I band, and consequently the H zone</em>
<em>- The A line remains unchanged</em>
<em>- Z lines come closer to each other (and this is due to the shortening of the I bands) </em>
The only changes that take place occur in the zones/areas in the sacromere (as mentioned), not in the filaments (actin and myosin) that make the up the sacromere; hence all other options are wrong.
Hope this helps!
 
        
             
        
        
        
Answer:
velocity during second d = 20.0 mi/h
Explanation:
Total distance travelled is 2d, with an average velocity of 30.0 mi/h you can express the time travelled in terms of d:
distance = velocity * time
time = distance / velocity
time = 2d/30.0
The time needed for the first d at 60.0 is:
time = d/60.0
The time in the second d you can get it by substracting both times (total time - time for the first d) 
second d time = 2d/30.0 - d/60.0
= 4d/60.0 - d/60.0
= 3d/60.0
and with the time (3d/60.0) and the distance travelled (d) you can get the velocity:
velocity = distance / time
velocity = d / (3d/60.0)
= 60.0/3 = 20.0 mi/h
 
        
             
        
        
        
The atom becomes positively charged.
EXPLANATION :
When all the electrons are removed from the atom, the atom contains only protons and neutrons. The neutron is a neutral nucleon. ...
Hence, the correct answer is that atom will be positively charged.