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It is assumed that each of the two automobiles involved in the collision described in Prob. 14.35 had been designed to safely withstand a test in which it crashed into a solid, immovable wall at the speed v0. The severity of the collision of Prob. 14.35 may then be measured for each vehicle by the ratio of the energy it absorbed in the collision to the energy it absorbed in the test. On that basis, show that the collision described in Prob. 14.35 is
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Vector Mechanics for Engineers: Dynamics
- b) A truck of total mass 18tonne descends a hill with a gradient of 1 in 14, i.e. a vertical movement of 1m for each 14m of movement along the slope. During this motion, the truck experiences a rolling resistance to its motion of 900N. Whilst travelling at a velocity of 54km/h, its brakes are applied, and the truck is brought uniformly to rest in a distance of 112m. During this period of constant deceleration, it may be assumed that the rolling resistance remains constant at 900N, this being in addition to the retarding force applied by the brakes. Calculate for the truck whilst it is slowing down: a) The vertical height through which it descends. b) Its decrease in potential energy. c) Its initial velocity in m/s. d) Its decrease in kinetic energy. e) The work done against the rolling resistance.arrow_forward7900 kg RAIL INES 6800 kg PROBLEM 12.11 A tractor-trailer is traveling at 90 km/h when the driver applies his brakes. Knowing that the braking forces of the tractor and the trailer are 16 kN and 60 kN, respectively, determine (a) the distance traveled by the tractor- trailer before it comes to a stop, (b) the horizontal component of the force in the hitch between the tractor and the trailer while they are slowing down. x-xo= 60.4 m FH = 19.16 kNarrow_forwardYou have been hired as an expert witness in a court case involving an automobile accident. A piece of a bullet was found in the accident. The force on (iv) The accident involved car A of mass 1900 kg which crashed into stationary car B of mass 1100 kg. The driver of car A applied his brakes 15 m before he crashed into car B. After the collision, car A slid 18 m while car B slid 30 m. The coefficient of kinetic friction between the locked wheels and the road was measured to be 0.60. Determine the velocity for each car after the collisions.arrow_forward
- PROBLEM 5.19 23. A skier starts with a speed of 2 m/s and skis straight down a slope with an angle of 15° relative to the horizontal. The coefficient of kinetic friction between her skis and the snow is 0.1. What is her speed after 10 s? 16.91 m/s² 17.91 m/s² с. 18.91 m/s2 d. 19.91 m/s² а. b.arrow_forwardThe design for a new cementless hip implant is to be studied using an instrumented implant and a fixed simulated femur. Assuming the punch applies an average force of 2 kN over a time of 2 ms to the 200-g implant, determine (a) the velocity of the implant immediately after impact, (b) the average resistance of the implant to penetration if the implant moves 1 mm before coming to rest.arrow_forwardThe design for a new cementless hip implant is to be studied using an instrumented implant and a fixed simulated femur. Assuming the punch applies an average force of 2 kN over a time of 2 ms to the 200 g implant determine (a) the velocity of the implant immediately after impact, (b) the average resistance of the implant to penetration if the implant moves 1 mm before coming to rest.arrow_forward
- During an Olympic 100-m sprint race, Usain Bolt, the world record holder in that race, quickly accelerates to his top speed of 12.4 m/s. Analysis of his technique has shown that each of his feet make contact with the ground for 0.0800 s, exerting a force of magnitude 2.80 x 10° N during this contact. This allows the 94.0 kg Bolt to leap forward and remain airborne for 0.120 s until the next foot touches the ground. (Ignore air resistance.) (a) What are the magnitudes of the horizontal and vertical components of the force (in N) Bolt's feet exert on the ground? (Round your answers to at least three significant figures.) horizontal N vertical (b) Assuming that the sprinter accelerates at a constant rate while his feet are in contact with the ground and does not slow down when he is airborne, by what amount does Bolt's horizontal speed (in m/s) increase with each step? (Round your answer to at least three significant figures.) m/s (c) Assuming that the sprinter's speed increases at a…arrow_forward113 Blocks on a spring. Two blocks with masses m₁ and m₂ are connected by a spring and are free to slide on a frictionless horizontal surface. The blocks are pulled apart along an x axis and then released from rest. At any later time, (a) what fraction frac₁ of the total kinetic energy of the system will block 1 have and (b) what fraction fracz will block 2 have? (c) If m₁ > m2,which block has more kinetic energy? 中arrow_forward*44. GO A 60.0-kg person, running horizontally with a velocity of +3.80 m/s, jumps onto a 12.0-kg sled that is initially at rest. (a) Ignoring the effects of friction during the collision, find the velocity of the sled and person as they move away. (b) The sled and person coast 30.0 m on level snow before coming to rest. What is the coefficient of kinetic friction between the sled and the snow?arrow_forward
- A small 5-kg sphere moves at a constant speed along the horizontal circular path. Note that ACB is a single wire passing through a ring at C attached to the sphere. Calculate the speed of the sphere, when 0₁ = 50°, d= 0.8 m, the radius of the circular path is 1.6207 m, and the tension in both portions of the wire is 43 N. Present your answer in m/sec using 3 significant figures. B Ꮎ 01arrow_forwardQ8: The 450-kg ram of a pile driver falls 1.4 m from rest and strikes the top of a 240-kg pile embedded 0.9 m in the ground. Upon impact the ram is seen to move with the pile with no noticeable rebound. Determine the velocity v of the pile and ram imme- diately after impact. Can you justify using the principle of conservation of momentum even though the weights act during the impact? | Ans: v = 3.42 m/s 14 m 0.9 marrow_forwardQuestion 3: Objects A and B are connected by a rope with fixed length of 7 ft. They start moving from rest at x = 0, being pulled by the constant 20-lb force. If the coefficient of kinetic friction 4 is 0.2 between both objects A, B and the contacting surface, what is the speed of object B when x = 4 ft? Neglect the friction at the pulley. WB= 20 lb B 3 ft x = 4 ft 20 lb W 12 lbarrow_forward
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