Complete Question:
Metal sphere A has a charge of − Q . −Q. An identical metal sphere B has a charge of + 2 Q . +2Q. The magnitude of the electric force on sphere B due to sphere A is F . F. The magnitude of the electric force on sphere A due to sphere B must be:
A. 2F
B. F/4
C. F/2
D. F
E. 4F
Answer:
D.
Explanation:
If both spheres can be treated as point charges, they must obey the Coulomb's law, that can be written as follows (in magnitude):
As it can be seen, this force is proportional to the product of the charges, so it must be the same for both charges.
As this force obeys also the Newton's 3rd Law, we conclude that the magnitude of the electric force on sphere A due to sphere B, must be equal to the the magnitude of the force on the sphere B due to the sphere A, i.e., just F.
R = ρ L/A. R= resistance, ρ= resistivity, L= length of the conductor. A = area of the conductor. Resistance is directly proportional to the length of the conductor. So if length of the conductor is decreased, resistance will also decrease. Hence A is the correct option
Answer:
6.4m/s
Explanation:
The total mechanical energy of the man is 1780J.
This mechanical energy is the energy due to the motion of the body and it is a form of kinetic energy.
Also, mass = 87kg
Kinetic energy = 
m v²
m is the mass
v is the velocity
1780 = x 87 x v²
v² = 40.9
v = 6.4m/s
Answer:
lowest level contains more energy
Explanation:
F = ma
<span>where </span>
<span>F = frictional force </span>
<span>m = mass of the block = 1.4 kg (given) </span>
<span>a = acceleration of the block = 1.25 m/sec^2 (given) </span>
<span>Substituting values, </span>
<span>F = (1.4)(1.25) </span>
<span>F = 1.75 N </span>
<span>By definition, </span>
<span>F = (mu)(Normal force) </span>
<span>where </span>
<span>mu = coefficient of friction </span>
<span>Normal force = mg = 1.4*9.8 = 13.72 </span>
<span>Again, substituting appropriate values, </span>
<span>1.75 = mu(13.72) </span>
<span>mu = 0.128</span>
