Sarah and maria made a telephone using two cans and a string. it was a very long string. maria went upstairs in her house and sarah stayed downstairs. maria spoke softly into the can. "i can hear you! ' sarah said back. how can this happen? a)sound waves travel through a vacuum. b)sound waves travel from high to low. c)sound waves travel through solids like the string. eliminated)maria talked so loudly that sarah could hear her without the phone.

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?

Alfred pushes on a heavy box, but cannot move it. the box has a lot of inertia motion friction gravity

Given the position vector of the particle r(t)=(t+1)i+(t^2−1)j+2t k, find the particle's velocity and acceleration vectors at t=1