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17

First remember that $k = \dfrac {1}{4 \pi \epsilon_r\epsilon_o}$ where $\epsilon_r \ge 1$ It is because a medium can be polarised by an external E-field. The dipoles so set up produce the external E-field produce an E-field in the opposite direction so the net E-field (the sum of the external and dipole produced E-fields) is smaller. Thus the force a given ...


10

In electromagnetism there are both positive and negative charges. Hence the force due to electric charges can be attractive or repulsive. Gravity, when treated as a classical force field, can only be attractive, there are not two types of "gravitational charge". What this means is that in electromagnetism, a given medium, may contain both positive and ...


5

So this depends very strongly on the shape of the slide. The easiest way to see this is to push it to its extreme: suppose one slide is purely vertical and has a length of 100 meters (i.e. $H = L$, then in the absence of friction getting to the bottom requires a free-fall time, which is gotten by solving $H - \frac12 g t_1^2 = 0$ to get a time $t_1 = ...


3

Modern high-end bowling balls are extremely non-homogeneous in construction. If you look around at vendor sites, you'll see that there's an off-center "dumbell" of different density from the body of the sphere. All sorts of eccentric motion can occur as a result.


2

You apparently expect the plot of force vs acceleration to be linear, but not everything you will plot (e.g. position versus time) will be linear. Another example: plot the mean orbital radius of the planets vs. the period of revolution the planets. It's not linear. But if you plot the log of the orbital radius versus the log of the period it will be ...


2

The net effect of the charging process is the movement of electron from one plate which then has a net positive charge to the other plate which then has a net negative charge. The battery facilitates this by creating an electric field in the wires and it is this electric field which applies forces on the electrons which makes them move. The movement of ...


2

This is harder than it sounds. There are three things to consider. For a very narrow tube, for example $\lt 1~\rm{mm}$ diameter, the surface tension will be able to support a column of liquid - even if the other end of the tube is open. The pressure difference that can be sustained across a curved liquid surface with radius of curvature $R$ is calculated ...


1

I would answer that: My mass is 80 kg. My weight is 784.1 N


1

Suppose given an equation of the form $$y = Cx^n.$$ If you plot $y$ vs $x$ then it would be hard to find the value of $C$ or $n$ by looking at it. But if we take log on both sides we get $$ log(y) = n ~log(x) + log(C).$$ Now plotting $log(y)$ vs $log(x)$ would give us a straight line with slope $n$ and intercept $log(C)$. In your question the relation is ...



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