9. carlos jumps out of a hovering helicopter. after he opens his parachute, his acceleration due to gravity decreases
to zero. this is because
a the force of air resistance becomes equal in magnitude to his weight.
b. the force of gravity has become zero.
c. air resistance must be zero
d. he must have struck the ground,

Aparticle of mass m is placed in a one-dimensional box of length l. the box is so small that the particle’s motion is relativistic, so that e p2/2m is not valid. (a) derive an expression for the energy levels of the particle using the relativistic energy–momentum relation and the quantization of momentum that derives from connement. (b) if the particle is an electron in a box of length l 1.00 1012 m, nd its lowest possible kinetic energy. by what percent is the nonrelativistic formula for the energy in error?