solutions_for_chapter_5

solutions_for_chapter_5 - 11. Picture the Problem: The car...

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11. Picture the Problem : The car is accelerated horizontally in the direction opposite its motion in order to slow it down from 16.0 m/s to 9.50 m/s. Strategy: Use equation 5-1 and the definition of acceleration to determine the net force on the car as it slows down. Then use equation 2-10 to find the distance traveled by the car as it slows down. Solution: 1. (a) Use equation 5-1 and the definition of acceleration to find the net force on the car: ( 29 ( 29 ( 29 ( 9.50 16.0 m/s ˆ 950 kg 51 1.20 s 5.1 kN opposite to the direction of motion m m t - = = = = - = v F a x r r r 2. (b) Use equation 2-10 to find the distance traveled by the car as it slows down: ( 29 ( 29 ( 29 1 1 0 2 2 16.0 9.50 m/s 1.20 s 15.3 x v v t ∆ = + ∆ = + = Insight: We must consider “950 kg” as having only two significant figures because the zero is ambiguous. That limits the net force to two significant figures, even though the acceleration ( 29 2 ˆ 5.42 m/s - x has three significant figures. 18. Picture the Problem : The free body diagrams for the car and the trailer is shown at right. The diagram assumes there is no friction. Strategy: In order to determine the forces acting on an object, you must consider only the forces acting on that object and the motion of that object alone. For the trailer there is only one force 1 F r exerted on it by the car, and it has the same acceleration (1.85 m/s 2 ) as the car. For the car there are two forces acting on it, the engine 2 F r and the trailer 1 - F r . Apply Newton’s Second and Third Laws as appropriate to find the requested forces. Solution:

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This note was uploaded on 01/05/2012 for the course CHEM 3321 taught by Professor Bean during the Spring '11 term at American Jewish University.

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solutions_for_chapter_5 - 11. Picture the Problem: The car...

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