Starting from rest, a 1.9x10-4 kg flea springs straightupward. while the flea is pushing off from the ground, the groundexerts an average upward force of 0.41 n on it. this force does1.8x10-4 j of work on the flea. (a)what is the flea's speed when it leaves the ground? (b) how far upward does the flea move while it ispushing off? ignore both air resistance and the flea's weight.

Glass is transparent to visibile light under normal conditions; however, at extremely high intensities, glass will absorb most of the light incident upon it. this works through a process known as multiphoton absorption. in this process, several photons are absorbed at the same time. if very intense light whose photons carry 2ev of energy is shined onto a material with a band gap of 4ev, that light can be absorbed through two-photon absorption, because two photons have the right amount of energy to bridge the band gap. what is the minimum number of photons of 800-nm light that are needed to equal or exceed the band gap of fused silica glass

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

Suppose that 27 j of work is needed to stretch a spring from its natural length of 6 m to a length of 9 m. (a) how much work is needed to stretch the spring from 12 m to 14 m? j (b) how far beyond its natural length will a force of 78 n keep the spring stretched?