Tutor profile: Vusal S.
Subject: Physics (Newtonian Mechanics)
The inertial mass of a particle is, by definition, the mass that appears in Newton’s second law. Consider free fall of a particle with gravitational mass m and inertial mass m' near the surface of a homogeneous planet having gravitational mass M and radius R. Express the gravitational acceleration a of the particle in terms of these quantities (Neglect any frictional forces).
The equation of motion is m'a = F where F is the gravitational force exerted by the plane F = G M m/R^2 Thus a = m/m' = GM /R^2
Subject: Physics (Electricity and Magnetism)
A capacitor is connected to a battery. If we move its plates further apart, work will be done against the electrostatic attraction between the plates. What will be the effect on the energy of the capacitor?
Since the battery remains connected, the potential difference V between the plates of the capacitor will remain constant. Now Since Capacitance depends on the distance between the plates, it will decrease with the movement. Now we know that Q=CV Now C is decreasing and V remains constant, the charge will decrease on the capacitor. Some charges from plates passing through the connecting wire will charge the battery. Thus some energy of the capacitor will be transferred to the battery. So energy of the capacitor will decrease. The work done done in moving apart the plates will be used up in this transference and dissipated in the form of heat in the connecting wires
One of the questions in Physics which students find hard to grasp: What is potential difference?
This is one of the definitions one may find: "Potential difference is the amount of work energy required to move an electric charge from one point to another". I tend to give an analogy to explain this concept. First of all, what is potential? It is an ability to do some work. If I lift an object against gravity to certain height from the Earth, it has now ability (or potential) to fall back to the Earth. At this height it has more potential (more ability) to fall than when it was at initial height. The difference in potentials (or abilities) between these two heights is known as potential difference.
needs and Vusal will reply soon.