SF-2 The force required to stretch (elongate) a spring is shown in the graph to the right. a) Find the spring constant K for this spring. b) The work required to stretch the spring an infinitesimal distance dx is given by: dWk-Fdx where F-Kx. Do the integral to find an expression for the work required to stretch the spring from elongation x₁ to elongation X2. c) Find the work in joules to stretch the spring 5.00cm from its unloaded length. d) Find the work in joules to stretch the spring from x₁=5.00cm to X2=10.00cm. Force (N) 45 40 35 30 25 20 15 10 5 0 0 1 2 3 4 5 6 7 8 Spring Elongation, x 9 10 (cm)

Select each of the true statements belowA. The kinetic energy can be negative.B. If the Moon revolves around Earth in a perfectly circular orbit, then Earth does do work on the Moon.C. Spring A is stiffer than B (kA>kB) . A person must do more work on the block connected to spring A if both springs are ideal and the blocks are pulled by the same amount.D. The work a person must do to raise a box onto a platform does not depend on how fast it is raised.E. The kinetic energy of an object does not depend on the direction of the motion involved.F. Work can be done in the absence of motion.G. The gravitational force is a conservative force.H. The kinetic energy of an object depends on the reference frame of the observer. I would really appreciate an explanation as to why each option is true or false, so I am sure I understand.

A force given by (figure 1). Calculate the work done by this force acting on an object as it moves from x=0 to x=3m.

A 1400-kg elevator is lifted at a constant speed of 1.5 m/s through a height of 25 m. Part A How much work is done by the tension in the elevator cable? Express your answer to two significant figures and include appropriate units. ? Value Units Submit Request Answer Part B How much work is done by gravity? Express your answer to two significant figures and include appropriate units. HẢ ? Value Units