What is the mass of the skateboard? A 47.4 kg students runs down the sideral and jumps with a horizontal speed of 4.2 m/s onto a stationary skateboard. The student and skateboard move down the side walk with a speed of 3.95 m/s. Show work please

Afeather of mass 0.001 kg falls from a height of 2 m. under realistic conditions, it experiences air resistance. based on what you know about friction, what can you say about the kinetic energy of the feather as it reaches the ground? acceleration due to gravity is g = 9.8 m/s2. a. ke < 0.0196 j b. ke = 00196 j c. je = 0 j d. ke > 0.0196 j

Unpolarized light whose intensity is 1.19 w/ is incident on a polarizer. (a) what is the intensity of the light leaving the polarizer? (b) if the analyzer is set at an angle of = 41.0∘ with respect to the polarizer, what is the intensity of the light that reaches the photocell?

Which is the correct symbol for an isotope of iodine with 53 protons and 78 neutrons?