For book kept on a shelf, the weight of the book in down direction is balanced by the normal force on the book by the shelf. hence the book kept on a shelf is an example of balanced force.

In case of air rushing out of balloon , the balloon experience a net force by the air coming out of it.

rolling over and falling off the bed , the object falls under gravity force.

a car speeding up accelerates. since it accelerates , it has net force on it.

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3 years ago

A parallel-plate capacitor has a voltage of 391 v applied across its plates, then the voltage source is removed. what is the vol

andrezito [222]

When the capacitor is connected to the voltage, a charge Q is stored on its plates. Calling $C_0$ the capacitance of the capacitor in air, the charge Q, the capacitance $C_0$ and the voltage ( $V_0=391 V$ ) are related by

$C_0 =\frac{Q}{V_0}$ (1)

when the source is disconnected the charge Q remains on the capacitor.

When the space between the plates is filled with mica, the capacitance of the capacitor increases by a factor 5.4 (the permittivity of the mica compared to that of the air):

$C=k C_0 = 5.4 C_0$