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At the bottom of an air track tilted at angle θ, a glider of mass m is given a push to make it coast a distance d up the slope as it slows clown and stops. Then the glider comes back down the track to its starting point. Now the experiment is repeated with the same original speed but with a second identical glider set on top of the first. The airflow from the track is strong enough to support the stacked pair of gliders so that the combination moves over the track with negligible friction. Static friction holds the second glider stationary relative to the first glider throughout the motion. The coefficient of static friction between the two gliders is µ,. What is the change in mechanical energy of the two-glider—Earth system in the up- and down-slope motion after the pair of gliders is released? Choose one. (a) –2µ,mg (b) —2mgd cos (c) –2µ,mgdcos θ (d) 0 (e) +2µ.,mgd cos θ
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Chapter 8 Solutions
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- If the net work done by external forces on a particle is zero, which of the following statements about the particle must be true? (a) Its velocity is zero. (b) Its velocity is decreased. (c) Its velocity is unchanged. (d) Its speed is unchanged. (e) More information is needed.arrow_forwardA particle moves in a medium under the influence of a retarding force equal to mk(υ3+ a2υ), where k and a are constants. Show that for any value of the initial speed the particle will never move a distance greater than π/2kaand that the particle comes to rest only for t → ∞.arrow_forwardAt the bottom of an air track tilted at angle , a glider of mass m is given a push to make it coast a distance d up the slope as it slows down and stops. Then the glider comes back down the track to its starting point. Now the experiment is repeated with the same original speed but with a second identical glider set on top of the first. The airflow from the track is strong enough to support the stacked pair of gliders so that the combination moves over the track with negligible friction. Static friction holds the second glider stationary relative to the first glider throughout the motion. The coefficient of static friction between the two gliders is s. What is the change in mechanical energy of the two-glider-Earth system in the up- and down-slope motion after the pair of gliders is released? Choose one. (a) 2smg (b) 2mgd cos (c) 2smgd cos (d) 0 (e) +2smgd cosarrow_forward
- If the four Pratt & Whitney PW4000 turbofan engines of a Boeing747-400 aircraft do 5.62 Million Joules of work during a takeoff run that is 3185 m long, calculate the total thrust during takeoff for each of the PW4000 engines. what is the approximate maximum thrust of each of the Boeing 747-400's engines during takeoff (in pounds-force)?arrow_forwardA block A, of mass m = 10 Kg, compresses a spring of constant K = 1000 N / m in a length x = 3 cm. Starting from rest, the block is released, which moves from that moment on a horizontal surface without friction until it collides with another block B of mass m = 40 Kg, which was at rest. (Perfectly inelastic shock) and together they go up the channel (inclined surface) without friction, to later continue along a second horizontal plane without friction, at a height h with respect to the first (see Figure). Determine the energy variation that occurs in the collision .arrow_forwardA block of mass m is initially at rest at the top of an inclined plane, which has a height of 4.8 m and makes an angle of θ = 27° with respect to the horizontal. After being released, it is observed to be traveling at v = 0.65 m/s a distance d after the end of the inclined plane as shown. The coefficient of kinetic friction between the block and the plane is μp = 0.1, and the coefficient of friction on the horizontal surface is μr = 0.2. a)What is the speed of the block, in meters per second, just after it leaves the inclined plane? b)Find the distance, d, in meters.arrow_forward
- Assume that the force of a bow on an arrow behaves like the spring force. In aiming the arrow, an archer pulls the drawstring back 62 cm from its rest position and holds it in position with a force of 170 N. If the mass of the arrow is 59 g and the "spring" is massless, what is the speed (in m/s) of the arrow immediately after it leaves the bow?arrow_forwardAn Atwood's machine consists of two different masses, both hanging vertically and connected by an ideal string which passes over a pulley. Let the masses be M1 and M2 and M2 = 2M1. Initially, M1 is held fixed a distance y below M2. Find the speed of the blocks when they are the same elevation (that is, the same horizontal position, by then each block has moved y/2).arrow_forwardA spring that has a force constant of 1050 N/m is mounted vertically on the ground. A block of mass 1.00 kg is dropped from rest from height of 1.65 m above the free end of the spring. By what distance does the spring compress?arrow_forward
- Three wooden blocks with masses of 2.0 kg, 12 kg, and 10 kg are attached by a rope and pulley system, asshown. When the 12-kg block is released from rest, it has a speed of 1.0 m/s after moving 1.0 m. Find thecoefficient of kinetic friction between the 12-kg block and the horizontal surface on which it rests. [Answer: µk = 0.56]arrow_forwardThe skateboarder in the drawing starts down the left side of the ramp with an initial speed of 6.3 ft/s. If nonconservative forces, such as kinetic friction and air resistance, are negligible, what would be the height "h" of the highest point (in meters) reached by the skateboarder on the right side of the ramp?arrow_forwarda 1.75-kg block at rest on a ramp of height h.When the block is released, it slides without friction to the bottomof the ramp, and then continues across a surface that is frictionlessexcept for a rough patch of width 10.0 cm that has a coefficientof kinetic friction mk = 0.640. Find h such that the block’s speedafter crossing the rough patch is 3.50 m>s.arrow_forward
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningClassical Dynamics of Particles and SystemsPhysicsISBN:9780534408961Author:Stephen T. Thornton, Jerry B. MarionPublisher:Cengage Learning