15-10. The 50-kg crate is pulled by the constant force P. If the crate starts from rest and achieves a speed of 10 m/s in 5 s, determine the magnitude of P. The coefficient of kinetic friction between the crate and the ground is uk 0.2. %3D P 30° Prob. 15-10

1 ) Derive a free body diagram with spring-mass-damper elements for given system. QUESTION 2 ) Derive equation of motion for given system in terms of m, c, k.

In a nutshell, a smaller rock is propelled into the air as a huge counterweight in the back falls down, effectively converting gravitational potential energy into kinetic energy for the rock and the weight. But, since the rock is smaller.. it is propelled at a much faster velocity! Let's say we wanted to hurl a 50 kg boulder at a castle wall 100 meters away. Our wooden structure for the trebuchet is 10 meters tall, so that is the maximum distance the counterweight can fall. Assuming the launch angle is a perfect 45 degrees, and the boulder is released from ground level, derive the needed mass of the counterweight that will give the boulder enough kinetic energy to reach the base of the castle walls. You may assume no energy is "lost" due to friction, and ALL the counterweight's gravitational potential energy is converted into the boulder's kinetic enerqy. (HINT: You will need to employ 2D kinematics to find the needed final velocity, then use that final velocity in an energy equation…

A long, thin, wire of uniform cross-section has Young's Modulus Y and mass density D. When laid horizontally on a bench its unstretched length is L. One end is attached to a fixed point and the rest of the wire is allowed to hang freely and vertically in the earth's gravitational field. Find the extension of the lowest end of the wire (i.e., the wire's length additional to L) due to gravitational force. The acceleration due to gravity is g.