Problem 7.41 The 1.5 kg physics book in figure is connected by a string to a 250

Question

Problem 7.41 The 1.5 kg physics book in figure is connected by a string to a 250 g coffee cup. The book is given a push up the slope and released with a speed of 2.7 m/s. The coefficients of friction are ?.-0.50 and ?,-0.20. (Figure 1) PartA How far does the book slide? Express your answer with the appropriate units. Value Units Figure 1 of 1 > Submit Request Answer Part B At the highest point, does the book stick to the slope, or d 20° stick to the slope slide back downhill Submit Request Answer

Explanation / Answer

(a) While the book slides upslope, we have downslope forces:

cup: Fc = mg = 0.250kg * 9.8m/s² = 2.45 N

book: Fb = mgsin? = 1.5kg * 9.8m/s² * sin20º = 5.03 N

friction: Ff = µmgcos? = 0.2 * 1.5kg * 9.8m/s² * cos20º = 2.76 N

for a total downslope force Fnet = 2.45+5.03+2.76 = 10.24 N

Total mass is m = 0.250+1.5 = 1.75kg,

so the acceleration is a = 10.24N / 1.75kg = 5.85 m/s² downslope.

v² = u² + 2as

0² = (2.7m/s)² - 2 * 5.85m/s² * s

s = 0.623 m ?

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