I am having a confusion in the following question-Q-To stimulate car accidents auto manufacturers study the collision of moving cars with mounted springs of different spring constants. consider a typical simulation with a car of mass 1000 kg moving with a speed 5m/s on a smooth road and colliding with a horizontally mounted spring of spring const-6.25*(10)^3 what is the maximum compression of the spring 1.when there is no friction and 2. when u=0.5 ?Now the first part is easy. we are able to find the kinetic energy which is converted to P.E. at max compression. so we get 12500 J =0.5*k*(x)^2 and then we get the compression x as 2.00 metres. But what about the second part? In this first and foremost lets consider the FBD which is my main problem in this question. why is the friction acting in the +ve x axis. if the wheels of the car are rolling the according to me the friction should be in the direction of the motion.

Jai Mahajan

11 Years agoGrade 12