Please answer my question

Two polarizers are oriented at 70∘∘ to one another. unpolarized light falls on them. what fraction of the light intensity is transmitted?

What is the name of the perceived change in a sound wave’s frequency due to motion between the observer and the sound source?

Four identical lab carts each have a mass of 200 kg. different masses are added to the carts and the velocities are measured. all carts move to the right.