A 4.0 m long thin rod is pinned so that it spins about its center. The rod has a rotational inertia of 8.0 kg m2 about this center. The rod has two 3.0 kg masses attached at each end. What force F must be applied to one end to make the system rotate with an angular acceleration of 4.0 rad/s2 about its center

If a rock is thrown upward on the planet mars with a velocity of 12 m/s, its height (in meters) after t seconds is given by h = 12t − 1.86t2. (a) find the velocity of the rock after two seconds. m/s (b) find the velocity of the rock when t = a. 12−3.72a m/s (c) when will the rock hit the surface? (round your answer to one decimal place.) t = s (d) with what velocity will the rock hit the surface? m/s