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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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Chapter 6 Solutions
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- 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_forwardYou push a .50kg block against a spring (k=3100 N/m),compressing it by .12m. The block is then released from rest and the spring pushes the block away. The spring and the block lose contact and the block collides with a second block of twice the mass. The two blocks slide together down a frictionless track consisting of a flat straightaway and a vertical, semi-circle of radius 40cm. What is the speed of the blocks when they have travelled halfway up the semicircle part of the track? What is the magnitude of the normal force on the two blocks at that same location?arrow_forwardThe figure shows a thin rod, of length L = 2.20 m and negligible mass, that can pivot about one end to rotate in a vertical circle. A heavy ball of mass m = 8.10 kg is attached to the other end. The rod is pulled aside to angle 00 = 8° and released with initial velocity V 0. (a) What is the speed of the ball at the lowest point? (b) Does the speed increase, decrease, or remain the same if %3D the mass is increased? 3.arrow_forward
- A 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_forwardAn amusing trick is to press a finger down on a marble on a horizontal table top, in such a way that the marble is projected along the table with an initial linear speed v and an initial backward rotational speed ω about a horizontal axis perpendicular to v. The coefficient of sliding friction between marble and top is constant. The marble has radius R. If the marble skids to a stop and then starts returning toward its initial position, with a final constant speed of 0.620v, what was ω in terms of v and R? Hint for part (b): When the marble rolls without slipping, the relationship between speed and angular speed is v = ωR.arrow_forwardTo test the speed of a bullet, you create a pendulum by attaching a 5.80 kg wooden block to the bottom of a 1.60 m long, 0.800 kg rod. The top of the rod is attached to a frictionless axle and is free to rotate about that point. You fire a 10 g bullet into the block, where it sticks, and the pendulum swings out to an angle of 39.0°. What was the speed of the bullet?arrow_forward
- A spring with spring constant k and equilibrium length zero is attached tothe top of a frictionless hoop of radius R. The spring is stretched and connected to a bead of mass m at the bottom of the hoop. At t = 0 the bead is given an initial speed v0 and the bead moves up the hoop. Find the speed of the bead as a function of position on hoop v(θ).arrow_forwardThe puck in the figure below has a mass of 0.260 kg. Its original distance from the center of rotation is 40.0 cm, and it moves with a speed of 90.0 cm/s. The string is pulled downward 15.0 cm through the hole in the frictionless table. Determine the work done on the puck. (Hint: Consider the change of kinetic energy of the puck.)arrow_forwardA car is going around a flat curve which has a radius of curvature of 87.3 m with a constant speed of 27.3 m/s. The car has a mass of 1410. kg. The coefficient of static friction between the tires and the road is μs = 0.975, while the coefficient of kinetic friction is k = 0.648. What is the work done by the static friction force between the tires and the road for the car to travel a distance of one quarter of the circumference of a circle with this radius?arrow_forward
- A 12-kg mass package is in a non-atmosphere asteroid of mass 1.7 x 1014 kg and radius 2,000 m. The package is released with a powerful spring whose stiffness is 315 N / m. After being launched, the package is observed to have a speed of 3.0 m / s when it is at a distance of 5,000 m from the center of the asteroid. Calculate how much the spring was compressed to launch the package?arrow_forwardNow Chandra and Darcel decide to try a problem. Suppose that the height of the incline is h = 16.0 m. Find the speed at the bottom for each of the following objects. solid sphere m/s spherical shell m/s hoop cylinder m/s m/s In a race, which object would win?arrow_forwardTab sLk A printing press has a roller 17 inches in diameter. A point on the roller's surface moves at a speed of 85 feet per second. What is the roller's angular speed? The roller's angular speed is radians per second. (Round your answer to the nearest hundredth.) Esc I 1 Q A 91°F Sunny 261 N @ 2 W S Alt X 3E D C STR 4 F C FS do 5 % T V OL G 6 B F7 H W & 7 P U N J 8 +00 8 F9 1 k M F10 ( 9 K O V LO F11 O L P All + 99+ F12 . V Parrow_forward
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