All of the following problems deal with Jimmy and his friend. Draw a FBD for each. Assume the total mass of Jimmy and his sled is 50kg. Disregard air resistance.
- Jimmy is sledding down the side of a hill, using his iPhone as an accelerometer. The phone measures his acceleration to be 2.5 m/s^2. What is the net force he is experiencing? (125 N)
- Jimmy is being pulled back up the hill by a "friend" who owes him $5. Assuming his friend applies 18N of force up the hill and gravity and friction each apply 8N of force down the hill, what is Jimmy's acceleration? (0.04 m/s^2)
- At the top of the hill, the snow is level and flat. Jimmy runs with his sled up to a speed of 3 m/s before diving onto it and sliding to a stop (still on the level part of the snow). Assuming it takes Jimmy 2 s to slide to a stop, what is his acceleration? What is the net force during these two seconds? What is applying the force? (-1.5 m/s^2, -75N, friction)
- Jimmy is being pushed horizontally across the level part of the snow at a constant velocity. If his "friend" applies 15N of force in order to maintain Jimmy's velocity, what is the coefficient of friction between Jimmy's sled and the snow? (0.03)
- Jimmy's "friend" finally gets tired of having to pull Jimmy around. Using the heel of his boot, he expeditiously pushes Jimmy down a 45 degree incline and into a grove of trees. Using the coefficient from #4, what will Jimmy's acceleration down the incline be? (-6.7 m/s^2)