Need with exercises 3,4,5

will give !

Ineed extreme for task 2. my student number is 571721. many to whoever solves this correctly, im in debt to you.

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.

When a vertical beam of light passes through a transparent medium, the rate at which its intensity i decreases is proportional to i(t), where t represents the thickness of the medium (in feet). in clear seawater, the intensity 3 feet below the surface is 25% of the initial intensity i0 of the incident beam. what is the intensity of the beam "10" feet below the surface? (give your answer in terms of i0. round any constants or coefficients to five decimal places.)