1. The problem statement, all variables and given/known data A child is playing with their Hot Wheel cars. They have set up a track which is initially horizontal but then ascends to a second horizontal section which is 50 cm higher than the initial track. The track is friction-less until the car reaches the upper section of the track where some spilled soft drink exerts a frictional force on the car. They launch the 100 gram cars on the lower horizontal section using a spring loading launcher which requires the spring to be compressed by 2 cm. (Use conservation of energy and work to solve this problem.) (25 marks) a. If the car is travelling at 1 m/s when it initially reaches the upper section of the track what is the spring constant of the launcher? b. If the coefficient of kinetic friction on the upper portion of the track is 0.4, how far does the car travel before it stops? c. Draw energy bar charts for: i. The initial situation (the car is in the spring loading launcher with the spring compressed), ii. When the car arrives at the start of the upper horizontal section, iii. When the car comes to a final stop. d. What work does the child need to do to compress the spring? e. How much work does the frictional force do? 2. Relevant equations Fsc,x= -k(x-xo) Fec,x=-mg Fk,12=(u,k)(Fn,12) 3. The attempt at a solution So I think I got part a)So since the track is frictionless we can assume the intial velocity before going up the inline= final velocity at the top of incline so there is no acceleration. The only force that the car has to overcome is the force of gravity. So i used Fec,x= mg=(100g)(1kg/1000g)(9.8m/s^2)=0.98N. This would also be the force that the spring has to exert on the car. So then i used Fsc,x=-k(x-xo) 0.98N=-k(-0.02m) k=49 b) for part b I am completely lost. I know I will probably have to use the equation Fk,12=(u,k)(Fn,12) but I don't know what the normal force is? Could someone explain that to me and how to figure that out please. c)i)this would be all potential energy ii)There would be kinetic energy, maybe some potential energy? and some thermal energy iii) This would all be converted to thermal energy d and e should be easy after I figure out the rest.