Answer: a) 73.41 10^-12 F; b)4.83* 10^3 N/C; c) 3.66 *10^3 N/C
Explanation: To solve this problem we have to consider the following: The Capacity= Charge/Potential Difference
As we know the capacity is value that depend on the geometry of the capacitor, in our case two concentric spheres.
So Potential Difference between the spheres is given by:
ΔV=-
Where E = k*Q/ r^2
so we have 
then
Vb-Va=k*Q(1/b-1/a)=kQ (ab/b-a)
Finally using C=Q/ΔV=ab/(k(b-a))
To caclulate the electric firld we first obtain the charge
Q=ΔV*C=120 V*73.41 10^-12 F=8.8 10^-9 C
so E=KQ/r^2 for both values of r
r=12.8 cm ( in meters)
r2=14.7 cm
E(r1)=4.83* 10^3 N/C
E(r2)=3.66 *10^3 N/C
F = (mass)(acceleration) = ma
m = 0.25 kg
Vi = 16 m/s
t = 2 s
Vf = 0 m/s (since it was put to stop)
a=(Vf-Vi)/t
a=(0-16)/2
a = 8 m/s^2 (decelerating)
F = ma = (0.25 kg)(8 m/s^2)
F = 2 N
<span>Hope
this answer will be a good h<span>elp for you.</span></span>
<span>a. A solid will gain kinetic energy and become a liquid.</span>
Answer:
90,000 J
Explanation:
Kinetic energy can be found using the following formula.

where <em>m </em>is the mass in kilograms and <em>v</em> is the velocity in m/s.
We know the object has a mass of 50 kilograms. We also know it is a traveling at a rate of 60 m/s. Velocity is the speed of something, so the velocity of the object is 60 m/s.
<em>m</em>=50
<em>v</em>=60
Substitute these values into the formula.

First, evaluate the exponent: 60^2. 60^2 is the same as multiplying 60, 2 times.
60^2=60*60=3,600

Multiply 50 and 3,600

Multiply 1/2 and 3,600, or divide 3,600 by 2.

Add appropriate units. Kinetic energy uses Joules, or J.

The kinetic energy of the object is 90,000 Joules