Answer:
0.0979 N/c
Explanation:
Electric field, E is given as a product of resistivity and current density
E=jP where P is resistivity and j is current density
But the current density is given as
where I is current and A is area and 
Substituting this into the first equation then 
Given diameter of 0.259 cm= 0.00259 m and the radius will be half of it which is 0.001295 m

Answer:
Explanation:
Convert the mass to kg:
375g = 375/1000kg = 0.375kg
F = ma
-20 = 0.375a
a = -20/0.375
a = -53
The object is accelerating at 53m/s/s backwards assuming that the forward motion is positive.
Answer:
0.0312J
Explanation:
Let x be the distance the staple moves:

And spring constant is 

Hence, the potential energy is 0.0312J