MasteringPhysics: Assignment 4 (Ch. 5, 6, and 7-Google Chrome Secure l https://s
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MasteringPhysics: Assignment 4 (Ch. 5, 6, and 7-Google Chrome Secure l https://session.masteringphysics.com/myct/itemView?assignmentProblemID-83897079 Assignment 4Ch 5 6 and Problem 6.51 - Enhanced - with Hints « previous 8 of 11 next Problem 6.51 Enhanced - with Hints Part A A 2.0 kg wood block is launched up a wooden ramp that is inclined at a 25 angle. The block's initial speed is 15 m/s The coefficient of kinetic friction of wood on wood is What vertical height does the block reach above its starting point? Express your answer to two significant figures and include the appropriate units. = 0.200 You may want to review ( page 131) For help with math skills, you may want to review. Hints h-8.0 n Submit My Answers Give Up Correct Part B What speed does it have when it slides back down to its starting point? Express your answer to two significant figures and include the appropriate units. Hints U= 16.13 Submit My Answers Give Up Incorrect: Trv Aaain: 3 attempts remaining Type here to search 2017-10-14Explanation / Answer
mass of block = 2.0 kg
weight of block = mg = 2.0(9.8) = 19.6 N
normal force against block = 19.6(cos 25) = 17.8 N
weight component parallel to plane = 19.6(sin 25) = 8.28 N
block's initial KE = 1/2mV² = (0.5)(2.0)(15)² = 225 J
friction force = (17.8)(0.20) = 3.56 N
total force opposing upward motion along plane = 3.56 + 8.28 = 11.84 N
displacement upward along plane = d
initial KE = work done by all opposing forces
225 = 11.84*d
d = 19 m along plane
ANS (a) = 19*(sin 25) = 8.03 m
b) GPE at top of plane = mgh = (2.0)(9.8)(8.03) = 157.4 J
KE at bottom (after being 8.03 m above ground) = 157.4 - 3.56(19) = 89.76 J
KE = 1/2mV² = 89.76
V² = 89.76*(2)/2.0 = 89.76
V = 9.47 m/s