Answer with Explanation:
We are given that
Resistance of solenoid,R=4.3 ohm
Magnetic field,B=
Current,I=4.6 A
Diameter of wire,d=0.5 mm=
Radius of wire,r=

Radius of solenoid,r'=1 cm=

Resistivity of copper,
We know that

Where 
Using the formula


Number of turns of wire=
Number of turns of wire=
Hence, the number of turns of the solenoid,N=799
Magnetic field in solenoid,B=






Length of solenoid=12.5 cm
1m=100 cm
Answer:
3200 has the fewest number of sig figs
Explanation:
sorry i was late
To develop this problem it is necessary to apply the concepts related to Gravitational Potential Energy.
Gravitational potential energy can be defined as

As M=m, then

Where,
m = Mass
G =Gravitational Universal Constant
R = Distance /Radius
PART A) As half its initial value is u'=2u, then



Therefore replacing we have that,

Re-arrange to find v,



Therefore the velocity when the separation has decreased to one-half its initial value is 816m/s
PART B) With a final separation distance of 2r, we have that

Therefore




Therefore the velocity when they are about to collide is 
In addition to acceleration of gravity we experience centrifugal acceleration away from the axis of rotation of the earth. this additional acceleration has value ac = r w^2 where w = angular velocity and r is distance from your spot on earth to the earth's axis of rotation so r = R cos(l) where l = 60 deg is the lattitude and R the earth's radius and w = 1 / (24hr x 3600sec/hr)
<span>now you look up R and calculate ac then you combine the centrifugal acc. vector ac with the gravitational acceleration vector ag = G Me/R^2 to get effective ag' = ag -</span>
<u>Answer:</u>
Work input = Work output * Work against friction is your answer so C
<u>Explanation:</u>
I hope this helps you :)