a bungee jumper jumps off a bridge and bounces up and down several times, she finally went up to rest 16 m below the bridge from which she just jumped. if her mass is 50 kg and the spring constant of the bungee cord is 35 n/m how much energy was lost due to air resistance while she was bouncing?

An object weighs 40n in air, weighs 20n when submerged in water and 30n when submerged in a liquid of unknown density. what is the density of the liquid?

Could someone . i have tried to solve myself but my calculation is off

Asheet of steel 1.5 mm thick has nitrogen atmospheres on both sides at 1200oc and is permitted to achieve a steady-state diffusion condition. the diffusion coefficient for nitrogen in steel at this temperature is 6 x 10- 11 m2 /s, and the diffusion flux is found to be 1.2 x 10-7 kg/m2 -s. also, it is known that the concentration of nitrogen in the steel at the high-pressure surface is 4 kg/m3 . how far into the sheet from this high-pressure side will the concentration be 2.0 kg/m3 ? assume a linear concentration profile.