Two skiers, Annie and Jack, start skiing from rest at different points on a hill

Question

Two skiers, Annie and Jack, start skiing from rest at different points on a hill at the same time. Jack, with mass 94 kg, skis from the top of the hill down a steeper section with an angle of inclination of 35degree. Annie, with mass 61 kg, starts from a lower point and skis a less steep section, with an angle of inclination of 20 degree. The length of the steeper section is 140 m. Determine the acceleration, velocity, and position vectors of the combined center of mass for Annie and Jack as a function of time before Jack reaches the less steep section. (Use the following variable as necessary: t, where t is the time before Jack reaches the less steep section.)

Explanation / Answer

Two skiers, Annie and Jack, start skiing from rest at different points on a hill at the same time. Jack, with mass 94 kg, skis from the top of the hill down a steeper section with an angle of inclination of 35°. Annie, with mass 63 kg, starts from a lower point and skis a less steep section, with an angle of inclination of 20°. The length of the steeper section is 150 m. The problem is asking to find the Acceleration , velocity , and position vector before jack reaches the less steep section. It would be great if some gave me a couple of hints on how to start this problem Here is a pic : http://s172.photobucket.com/albums/w30/afghanplayr/?action=view&current=8-p-032-alt.gif we are ignoring a lot a friction here. 150m *sin(35) = 86m vertical drop 150 cos(35) =122.9 m advance horizontal = position the vertical component of mass is 86/150 *94kg and the vertical acceleration will be 86/150*9.81 m/sec^2 = 5.62m/sec^2 v =1/2At^2 86 = 1/2 *5.62*t^2 t=5.53s V upon arrival at less steep section = 5.53*5.62 =31.1 m/s

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