problem05_p107

# University Physics with Modern Physics with Mastering Physics (11th Edition)

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5.107: a) The forces on the car are the air drag force 2 D Dv f = and the rolling friction force . r mg μ Take the velocity to be in the x + -direction. The forces are opposite in direction to the velocity. x x ma F = gives ma mg Dv = - - r 2 μ We can write this equation twice, once with s m 32 = v and 2 s m 42 . 0 - = a and once with s m 24 = v and . m/s 30 . 0 2 - = a Solving these two simultaneous equations in the unknowns D and r gives 015 . 0 r = and . m s N 36 . 0 2 2 = D b) β mg n cos = and the component of gravity parallel to the incline is , sin
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Unformatted text preview: β mg where . 2 . 2 ° = β For constant speed, . 2.2 cos 2.2 sin 2 r =-°-° Dv mg mg Solving for v gives . s m 29 = v c) For angle cos sin , 2 r =--Dv mg mg β and D β β mg v ) cos (sin r-= The terminal speed for a falling object is derived from , 2 t =-mg Dv so . t D mg v = β β v v cos sin r t-= And since β β v v μ cos ) 015 . ( sin , 015 . t r-= =...
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