8. A locomotive is pulling 12 freight cars, each of which is loadedwith roughly

Question

8. A locomotive is pulling 12 freight cars, each of which is loadedwith roughly the same weight. The mass of each can betaken to be 37,000 kg. If the train is accelerating at 0.73m/s2 on a level track, what is the tension in thecoupling between the second and third cars? The car nearest thelocomotive is counted as the first.
9. A 200g hockey puck is launced up a metal ramp that isinclined at a 300 angle. The coefficients of staticand kinetic friction between the puck and the rampare s=0.40 and k=0.30, and the puck's initialvelocity at the base is 3.8 m/s parallel to the sloping surface ofthe ramp. What speed does the puck have when it slides back down toits starting point?
10. A weightless spring of force constant 2.50 N/cm is 15.0 cmlong when nothing is attached to it. It is now used to pullhorizontally on a 12.5 kg box on a smooth horizontal floor. Youobserve that the box starts from rest and moves 96.0 cm during thefirst 1.60 s of its motion. How long is the spring during thismotion?
11. A Ferris wheel has radius 5.0 m and makes one revolutionin 8.0 seconds. A person weighing 670 N is sitting on one of thebenches attached at the rim of the wheel. What is the apparentweight (the normal force exerted on her by the bench) of the personas she passes through the highest point of her motion?
9. A 200g hockey puck is launced up a metal ramp that isinclined at a 300 angle. The coefficients of staticand kinetic friction between the puck and the rampare s=0.40 and k=0.30, and the puck's initialvelocity at the base is 3.8 m/s parallel to the sloping surface ofthe ramp. What speed does the puck have when it slides back down toits starting point?
10. A weightless spring of force constant 2.50 N/cm is 15.0 cmlong when nothing is attached to it. It is now used to pullhorizontally on a 12.5 kg box on a smooth horizontal floor. Youobserve that the box starts from rest and moves 96.0 cm during thefirst 1.60 s of its motion. How long is the spring during thismotion?
11. A Ferris wheel has radius 5.0 m and makes one revolutionin 8.0 seconds. A person weighing 670 N is sitting on one of thebenches attached at the rim of the wheel. What is the apparentweight (the normal force exerted on her by the bench) of the personas she passes through the highest point of her motion?

Explanation / Answer

8>    The tension in coupling between 2nd&3rd car=10*37000*0.73=270100 kg-m/s2 [Ans.] 10>F=12.5*f   [F=force,f=acceleration]       froms=u*t+0.5*f*t2             96=0+0.5*f*(1.60)2              f=75 cm/s2         F=12.5*75=937.5 kg-cm/s2=937.5*10-2kg-m/s2=k*x [k=spring constant, x=elongation inspring]                                                                                       =2.50*100*x                                            x=3.75 cm          During the motion, length of the spring=15+3.75=18.75cm     [Ans.] 11>=2/T=2/8=/4        when she passes thehighest point of her motion, the apparent weight of theperson=(mg-mr2)                                                                                                                                    =670-670/9.807*5*(/4)^2                                                                                                                                  =459.288 N   [Ans.]         F=12.5*75=937.5 kg-cm/s2=937.5*10-2kg-m/s2=k*x [k=spring constant, x=elongation inspring]                                                                                       =2.50*100*x                                            x=3.75 cm          During the motion, length of the spring=15+3.75=18.75cm     [Ans.] 11>=2/T=2/8=/4        when she passes thehighest point of her motion, the apparent weight of theperson=(mg-mr2)                                                                                                                                    =670-670/9.807*5*(/4)^2                                                                                                                                  =459.288 N   [Ans.]

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