A 42 kg box is being pushed a distance of 7.0 m across the floor by a force P whose magnitude is 155 N. The force P is parallel to the displacement of the box. The coefficient of kinetic friction is 0.25. Determine the work done on the box by each of the four forces that act on the box. Be sure to include the proper plus or minus sign for the work done by each force. applied force  J frictional force  J normal force  J gravity  J

A girl and a boy each exert a force to move a crate horizontally a distance of 13m at a constant speed. The girl's applied forced is 75N [22° below the horizontal]. The tension in the rope pulled by the boy is 75N [32° above the horizontal]. Determine the work done by the boy and the girl. Determine the force of friction and the work done by friction. If the coefficient of kinetic friction between the box and the floor is 0.5, what is the mass of the crate? Answer: W girl Fil As = (75cos 22° N)(13m) -9.04×10°J Froy As = (75cos 32°N)(13m) 8.27x10² J W boy boy.x Constant speed means a= 0, which means net work done is also zero. As a result, W, =-(9.04x10² +8.27×10°)J=-1.73×10'J. W, = F,As=F, -133N. F = µF→Fy 266N . F =mg -72sin 22° -75 sin 32° m 34kg Source: modified from Nelson, Physics 12, 2002, p.183, Section 4.1, #5

This is one question with two parts The force required to stretch a Hooke’s-law spring varies from 0N to 32.5N as we stretch the spring by moving one end 7.56 cm from its unstressed position. Find the force constant of the spring Answer in units of N/m Part two: find the work done in stretching the spring answer in units of J

A 268-kg crate is being pushed across a horizontal floor by a force P that makes an angle of 40.1 ° below the horizontal. The coefficient of kinetic friction is 0.248. What should be the magnitude of P, so that the net work done by it and the kinetic frictional force is zero? Number i eTextbook and Media Save for Later Units < 0 Attempts: 0 of 5 used Submit Answer