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Review. A piece of putty is initially located at point A on the rim of a grinding wheel rotating at constant angular speed about a horizontal axis. The putty is dislodged from point A when the diameter through A is horizontal. It then rises vertically and returns to A at the instant the wheel completes one revolution. From this information, we wish to find the speed v of the putty when it leaves the wheel and the force holding it to the wheel. (a) What analysis model is appropriate for the motion of the putty as it rises and falls? (b) Use this model to find a symbolic expression for the time interval between when the putty leaves point A and when it arrives back at A, in terms of v and g. (c) What is the appropriate analysis model to describe point A on the wheel? (d) Find the period of the motion of point A in terms of the tangential speed v and the radius R of the wheel. (e) Set the time interval from part (b) equal to the period from part (d) and solve for the speed v of the putty as it leaves the wheel. (f) If the mass of the putty is m, what is the magnitude of the force that held it to the wheel before it was released?
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Physics for Scientists and Engineers
- A small particle of mass m is pulled to the top of a friction less half-cylinder (of radius R) by a light cord that passes over the top of the cylinder as illustrated in Figure P7.15. (a) Assuming the particle moves at a constant speed, show that F = mg cos . Note: If the particle moves at constant speed, the component of its acceleration tangent to the cylinder must be zero at all times. (b) By directly integrating W=Fdr, find the work done in moving the particle at constant speed from the bottom to the top of the hall-cylinder. Figure P7.15arrow_forwardAn astronaut lands on a newly-discovered planet (without an atmosphere). As an experiment, she throws vertically upwards a pure vanadium sphere of radius 2.0 cm and density 5.5 × 103 kg m3 with an initial speed of 3.0 ms 1. The point of release is 1.2 m above the ground. She observes the sphere to travel 4.8 m before it starts falling to the ground. Calculate the kinetic energy of the projectile just as it hits the ground.arrow_forwardTo form a pendulum, a 0.050 kg ball is attached to one end of a rod of length 1.2 m and negligible mass, and the other end of the rod is mounted on a pivot. The rod is rotated until it is straight up, and then it is released from rest so that it swings down around the pivot. When the ball reaches its lowest point, what are (a) its speed and (b) the tension in the rod? Next, the rod is rotated until it is horizontal, and then it is again released from rest. (c) At what angle from the vertical does the tension in the rod equal the weight of the ball? (d) If the mass of the ball is increased, does the answer to (c) increase, decrease, or remain the same? (a) Number i 4.8e0 (b) Number i 1.4e0 (c) Number i 19. (d) increase Units Units Units m/s N °(degrees)arrow_forward
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- To form a pendulum, a 0.092 kg ball is attached to one end of a rod of length 0.84 m and negligible mass, and the other end of the rod is mounted on a pivot. The rod is rotated until it is straight up, and then it is released from rest so that it swings down around the pivot. When the ball reaches its lowest point, what are (a) its speed and (b) the tension in the rod? Next, the rod is rotated until it is horizontal, and then it is again released from rest. (c) At what angle from the vertical does the tension in the rod equal the weight of the ball? (d) If the mass of the ball is increased, does the answer to (c) increase, decrease, or remain the same? (a) Number i (b) Number (c) Number (d) Units Units Units #arrow_forwardA porter governor, its central load is 18 kg and the weight of each ball is 2 kg. The top arms are 25 cm while the bottom arms are each 30 cm long and all arms pivoted on the axis of rotation. The friction of the sleeve is 14 N. If the top arms make 45 ° with the axis of rotation in equilibrium position, find the speed of the governor at that position.arrow_forwardTo form a pendulum, a 0.024 kg ball is attached to one end of a rod of length 0.70 m and negligible mass, and the other end of the rod is mounted on a pivot. The rod is rotated until it is straight up, and then it is released from rest so that it swings down around the pivot. When the ball reaches its lowest point, what are (a) its speed and (b) the tension in the rod? Next, the rod is rotated until it is horizontal, and then it is again released from rest. (c) At what angle from the vertical does the tension in the rod equal the weight of the ball? (d) If the mass of the ball is increased, does the answer to (c) increase, decrease, or remain the same? (a) Number i Units (b) Number i Units (c) Number i Unitsarrow_forward
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