Carlos has eight marbles that are all the same size. he knows that one marble has a mass of 10 grams. to find out the total mass of all his marbles together, he adds 8 tens and gets a total of 80 grams. why does this method of finding the total mass work.

Karen is running forward at a speed of 9 m/s. she tosses her sweaty headband backward at a speed of 20 m/s. the speed of the headband, to the nearest whole number relative to a stationary observer watching karen

Tafari worked one summer on a ship that set weather buoys in the ocean. he watched how one of the buoys moved in the water. describe which parts of the wave would cause the buoy to bob up and down. which wave property determined how fast the buoys bobbed in the water? he observed that when the wind blew harder, the ocean waves were larger, and the buoys moved away from the ship. what effect, if any, did the waves have on how far the buoys moved? explain your answer.

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