EXAMPLE 6.2GOAL Find an impulseand estimate a force in acollision of a moving objectwith a stationary object.How Good Are the Bumpers?PROBLEM In a crashtest, a car of mass-15.0 m/s+2.60 m/sSOLUTION(A) Find the impulse delivered to the car.Calculate the initial and final momentaof the car.The impulse is just the differencebetween the final and initial momenta.Before1.50 x 10³ kg collides witha wall and rebounds as inthe figure. The initial andfinal velocities of the carare v₁ = -15.0 m/s and vf= 2.60 m/s, respectively.If the collision lasts for0.150 s, find (a) theimpulse delivered to thecar due to the collision and (b) the size and direction of the average force exerted on the car.a(a) This car's momentum changes as a result of its collisionwith the wall. (b) In a crash test (an inelastic collision),much of the car's initial kinetic energy is transformed intothe energy it took to damage the vehicle.(B) Find the average force exerted on the car.Apply the impulse-momentumAfterSTRATEGY This problem is similar to the a golf club striking a stationary golf ball, except that the initialand final momenta are both nonzero. Find the momenta and substitute into the impulse-momentumtheorem, solving for Fav.P₁ = mv; ==ⒸVolvo Car CorporationF =НЬ4257= -2.25 x 104 kg. m/sPf = mvf = (1.50 × 10³ kg)(+2.60 m/s)= +0.390 x 104 kg. m/sApI = Pf - Pi+0.390 x 104 kg · m/s - (-2.25 x 104 kg • m/s)I = 2.64 x 104 kg. m/s(1.50 × 10³ kg)(-15.0 m/s)2.64 x 104 kg. m/s= +1.76 x 105 N REMARKS When the car doesn't rebound off the wall, the average force exerted on the car is smallerthan the value just calculated. With a final momentum of zero, the car undergoes a smaller change inmomentum.QUESTION When a person is involved in a car accident, why is the likelihood of injury greater in ahead-on collision as opposed to being hit from behind? Answer using the concepts of relative velocity,momentum, and average force. (Select all that apply.)The momentum of the driver relative to the ground is greater in a head-on collision.The average force on the driver is greater in the head-on collision.The change in momentum is greater in the head-on collision.The collapse of the crumple zone in the front of the car occurs only in the head-on collision.The velocity of the driver relative to the ground is greater in a head-on collision.оооPRACTICE ITUse the worked example above to help you solve this problem. In a crash test, a car of mass1.41 x 10³ kg collides with a wall and rebounds as shown in the figure. The initial and final velocities ofthe car are v; = -15.5 m/s and vf = 2.35 m/s, respectively. If the collision lasts for 0.155 s, find thefollowing.(a) the impulse delivered to the car due to the collisionkg. m/s(b) the size of and direction of the average force exerted on the car (Indicate the direction withthe sign of your answer.)NEXERCISEHINTS: GETTING STARTED I I'M STUCK!Use the values from PRACTICE IT to help you work this exercise. Suppose the car doesn't rebound off thewall, but the time interval of the collision remains at 0.155 s. In this case, the final velocity of the car iszero. Find the average force exerted on the car. (Indicate the direction with the sign of your answer.)N

Practice Question: Given: The mass of the car is 1.41x103 kg. The initial and final velocity of the…

Use the worked example above to help you solve this problem. In a crash test, a car of mass 1.41 x 10³ kg collides with a wall and rebounds as shown in the figure. The initial and final velocities of the car are v; = -15.5 m/s and vf = 2.35 m/s, respectively. If the collision lasts for 0.155 s, find the following. (a) the impulse delivered to the car due to the collision kg. m/s (b) the size of and direction of the average force exerted on the car (Indicate the direction with the sign of your answer.) N

Use the worked example above to help you solve this problem. In a crash test, a car of mass 1.41 x 10³ kg collides with a wall and rebounds as shown in the figure. The initial and final velocities of the car are v; = -15.5 m/s and vf = 2.35 m/s, respectively. If the collision lasts for 0.155 s, find the following. (a) the impulse delivered to the car due to the collision kg. m/s (b) the size of and direction of the average force exerted on the car (Indicate the direction with the sign of your answer.) N

College Physics

11th Edition

ISBN:9781305952300

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter1: Units, Trigonometry. And Vectors

Section: Chapter Questions

Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...

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