4. Zyan is trying to swim across the English Channel in a north to south direction at 5km/h. There is a 2km/h west to east current in the channel. What is his
resultant swimming velocity?

Let f(x) = x4- 8x2 . find the relativeextrema of this function using the second derivative test.

Unpolarized light falls on two polarizer sheets whose transmission axes are at right angles. a third polarizer is placed between the first two so that its axis makes a 52-degree angle with the axis of the first polarizer. a) what fraction of the incident light intensity is transmitted through the first polaroid? b) what fraction of the incident light intensity is transmitted through the second polaroid? c) what is the angle of polarization of the light that enters the third polaroid? d) what fraction of the incident light intensity is transmitted through the third polaroid. e) what happens if the middle polaroid is removed?

The ozone hole appears in antarctica during