A uniform, thin rod hangs vertically at rest from a frictionless axle attached to its top end. The rod has a mass of 0.780 kg and a length of 1.54 m. (Assume a coordinate system where the +y-direction is up and the +x-direction is to the right. The rod is free to swing about the axle in the x- y plane.) (a) You take a hammer and strike the bottom end of the rod. At the instant the hammer strikes, the force it applies to the rod is (15.71) N. What is the acceleration (in m/s²) of the rod's center of mass at this instant? (Express your answer in vector form.) m/s² a = (b) What is the horizontal force (in N) that the axle exerts on the rod at this same instant? (Express your answer in vector form.) F = N (c) The rod then returns to hanging at rest. You again strike the rod with the hammer, applying the same force, but now you strike it at its midpoint. What now is the acceleration of the center of mass (in m/s²) at the instant of impact? (Express your answer in vector form.) m/s² a = (d) What is the horizontal force (in N) that the axle exerts on the rod when the rod is struck at the midpoint? (Express your answer in vector form.) F = N (e) You wish to find a point on the rod where you can strike it with the hammer so that the axle exerts no horizontal force on the rod. How far (in m) is this point from the top of the rod? This point is called the center of percussion. m

A solid cylinder of mass 2.0 kg and radius 20 cm is rotating counterclockwise around a vertical axis through its center at 600 rev/min. A second solid cylinder of the same mass and radius is rotating clockwise around the same vertical axis at 900 rev/min. If the cylinders couple so that they rotate about the same vertical axis, what is the angular velocity of the combination?

During a certain time interval, the angular position of a swinging door is described by = 5.00 + 10.0t + 2.00t2, where is in radians and t is in seconds. Determine the angular position, angular speed, and angular acceleration of the door (a) at t = 0 and (b) at t = 3.00 s.

A wheel 2.00 m in diameter lies in a vertical plane and rotates about its central axis with a constant angular acceleration of 4.00 rad/s2. The wheel starts at rest at t = 0, and the radius vector of a certain point P on the rim makes an angle of 57.3 with the horizontal at this time. At t = 2.00 s, find (a) the angular speed of the wheel and, for point P, (b) the tangential speed, (c) the total acceleration, and (d) the angular position.

As shown in Figure OQ10.9, a cord is wrapped onto a cylindrical reel mounted on a fixed, frictionless, horizontal axle. When does the reel have a greater magnitude of angular acceleration? (a) When the cord is pulled down with a constant force of 50 N. (b) When an object of weight 50 N is hung from the cord and released. (c) The angular accelerations in parts (a) and (b) are equal. (d) It is impossible to determine. Figure OQ10.9

A long, uniform rod of length L and mass M is pivoted about a frictionless, horizontal pin through one end. The rod is released from rest in a vertical position as shown in Figure P10.65. At the instant the rod is horizontal, find (a) its angular speed, (b) the magnitude of its angular acceleration, (c) the x and y components of the acceleration of its center of mass, and (d) the components of the reaction force at the pivot. Figure P10.65

Figure P10.16 shows the drive train of a bicycle that has wheels 67.3 cm in diameter and pedal cranks 17.5 cm long. The cyclist pedals at a steady cadence of 76.0 rev/min. The chain engages with a front sprocket 15.2 cm in diameter and a rear sprocket 7.00 cm in diameter. Calculate (a) the speed of a link of the chain relative to the bicycle frame, (b) the angular speed of the bicycle wheels, and (c) the speed of the bicycle relative to the road. (d) What pieces of data, if any, are not necessary for the calculations? Figure P10.16

Two particles of mass m1 = 2.00 kgand m2 = 5.00 kg are joined by a uniform massless rod of length = 2.00 m(Fig. P13.48). The system rotates in thexy plane about an axis through the midpoint of the rod in such a way that theparticles are moving with a speed of 3.00 m/s. What is the angular momentum of the system? FIGURE P13.48

A space station is constructed in the shape of a hollow ring of mass 5.00 104 kg. Members of the crew walk on a deck formed by the inner surface of the outer cylindrical wall of the ring, with radius r = 100 m. At rest when constructed, the ring is set rotating about its axis so that the people inside experience an effective free-fall acceleration equal to g. (See Fig. P10.52.) The rotation is achieved by firing two small rockets attached tangentially to opposite points on the rim of the ring. (a) What angular momentum does the space station acquire? (b) For what time interval must the rockets be fired if each exerts a thrust of 125 N? Figure P10.52 Problems 52 and 54.

Figure OQ10.8 shows a system of four particles joined by light, rigid rods. Assume a = b and M is larger than m. About which of the coordinate axes does the system have (i) the smallest and (ii) the largest moment of inertia? (a) the x axis (b) the y axis (c) the z axis. (d) The moment of inertia has the same small value for two axes. (e) The moment of inertia is the same for all three axes. Figure OQ10.8