The lower corner of a leaf in a book is folded over so as to reach the inner edge of the page. Show that the fraction of the width folded over when the area of the folded part is minimum is `2//3.`

If a leaf of a book is folded so that one corner moves along an opposite side, then prove that the line of crease will always touch parabola.

An electric field of magnitude 1000 NC ^(-1) is produced between two parallel platees having a separation of 2.0 cm as shown in figure(29.E4) (a) What is the potential difference between the plates? (b) With what minimum speed should an electron be projected from the lower plate in the direction of the field so that it may reach the upper plate? ( c) Suupose the electron is projected from the lower plate with the speed calculated in part (b) . The direction of projection makes an angle of 60@ with the field. Find the mazimum height reached by the electron.

A metal plate of area 0.10 m^(2) is connected to a 0.01 kg mass via a string that passes over an ideal pulley (considered massless and frictionless), A liquid with a film thickness of 0.3 mm is placed between the plate and the table. When released the plate moves to the right with a constant speed of 0.085 ms^(-1) . Find the coefficient of viscosity of the liquid.