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Zorch, an archenemy of Superman, decides to slow Earth's rotation to once per 28.0 h by exerting an opposing force at and parallel to the equator. Superman is not immediately concerned, because he knows Zorch can only exert a force of
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- There is a CD-rom that's spinning a CD at 2,000 rpm. There is a bit of dirt, weighing 0.220 g, attached to the CD 3.50 cm from the centre. What must the force of friction between the CD and the dirt be so that the bit of dirt continues to rotate in a circle and doesn't fly off? Give your answers in units of mN (millinewton), to three significant figuresarrow_forwardOn the International Space Station an object with mass m = 440 g is attached to a massless string of length L = 0.61 m. The string can handle a tension of T = 5.8 N before breaking. The object undergoes uniform circular motion, being spun around by the string horizontally.What is the maximum speed v the mass can have before the string breaks? Give your answer in units of m/s.arrow_forwardA person pushing a uniformly-loaded 31.7 kg wheelbarrow of length L with pushing force P is attempting to get it over a step. The maximum horizontal force that the person can apply is P, = 233 N. What is the maximum height h of the step, expressed as a fraction n of the wheel's radius R. that the person can get the wheelbarrow over? The gravitational acceleration is g = 9.81 m/s². 8459 R Incorrect hnRarrow_forward
- Two uniform spheres, each of mass 0.260 kg, are fixed at points A and B (Fig. ). Find the magnitude and direction of the initial acceleration of a uniform sphere with mass 0.010 kg if released from rest at point P and acted on only by forces of gravitational attraction of the spheres at A and B.arrow_forwardThree uniform spheres are located at the corners of an equilateral triangle. Each side of the triangle has a length of 1.35 m. Two of the spheres have a mass of 2.72 kg each. The third sphere (mass unknown) is released from rest. Considering only the gravitational forces that the spheres exert on each other, what is the magnitude of the initial acceleration of the third sphere?arrow_forwardA small block with mass 0.0300 kg slides in a vertical circle of radius 0.425 m on the inside of a circular track. During one of the revolutions of the block, when the block is at the bottom of its path, point A, the magnitude of the normal force exerted on the block by the track has magnitude 3.90 N . In this same revolution, when the block reaches the top of its path, point B, the magnitude of the normal force exerted on the block has magnitude 0.675 N . 1) How much work was done on the block by friction during the motion of the block from point A to point B?arrow_forward
- A small block with mass 0.0300 kg slides in a vertical circle of radius 0.550 m on the inside of a circular track. During one of the revolutions of the block, when the block is at the bottom of its path, point A, the magnitude of the normal force exerted on the block by the track has magnitude 3.75 N. In this same revolution, when the block reaches the top of its path, point B, the magnitude of the normal force exerted on the block has magnitude 0.685 N. Part A How much work was done on the block by friction during the motion of the block from point A to point B? Express your answer with the appropriate units. W friction = Submit μA Value Request Answer Units ?arrow_forwardAliens declare war on Earth by dropping an asteroid on our planet. The asteroid starts at rest from a distance of 37 x 106 m from the center of Earth. Calculate the speed with which the asteroid hits Earth's surface, in km/s. Use that G = 6.7 x 10-11 N m2 / kg2, MEarth = 6 x 1024 kg, and REarth = 6 x 106 m. (Please answer to the fourth decimal place - i.e 14.3225)arrow_forwardA sample of blood is placed in a centrifuge of radius 16.0 cm. The mass of a red blood cell is 3.0×10−163.0×10−16 kg, and the magnitude of the force acting on it as it settles out of the plasma is 4.0×10−114.0×10−11 N. At how many revolutions per second should the centrifuge be operated?arrow_forward
- An 80 kg person riding a Ferris wheel moves in a vertical circular trajectory of radius 6 m. As the person reaches the lowest point, a scale that the person is sitting on reads 920 N. There is nothing else in contact with the person. The person's speed is ____ m/s.arrow_forwardTracking some asteroids in our solar system by investigating the gravitational attraction between three asteroids that they find interesting. The tracking system uses a 2 dimensional grid system so that the scientists know where the asteroids are located. Asteroid 1 is located at the origin and has a mass of 4.5 x 1010 kg. Asteroid 2 has position coordinates of x2 = -200 km, y2 = -390 km and has a mass of 5.5 x 1010 kg. Asteroid 3 has position coordinates of x3 = 0 km, y3 = +410 km and has a mass of 6.0 x 1010 kg. What is the direction of the total gravitational force vector for asteroid 1? The angle will subtend an arc starting at the positive x axis going counter clockwise and ending at the total gravitational force vector for asteroid 1.arrow_forwardThe physics of circular motion sets an upper limit to the speed of human walking. (If you need to go faster, your gait changes from a walk to a run.) If you take a few steps and watch what's happening, you'll see that your body pivots in circular motion over your forward foot as you bring your rear foot forward for the next step. As you do so, the normal force of the ground on your foot decreases and your body tries to "lift off" from the ground. A. A person's center of mass is very near the hips, at the top of the legs. Model a person as a particle of mass m at the top of a leg of length L. Find an expression for the person's maximum walking speed vmax Express your answer in terms of the variables L and appropriate constants. b.)Evaluate your expression for the maximum walking speed of a 70 kg person with a typical leg length of 70 cm . Give your answer in m/s. c.) Give your answer in mph.arrow_forward
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning