Question 1:An extremely light, drivable car with a mass of only 9.50kg was built in London. Suppose that the wheels of the car are locked, so that the car no longer rolls. If the car is pushed up a 30.0 degree slope by an applied force of 80.0N, the net acceleration of the car is 1.64 m/s^2. What is the coefficient of kinetic friction between the car and the incline? Question 2:Cleopatra's Needle, an obelisk given by the Egyptian government to Great Britain in the nineteenth century, is 20+ m tall and has a mass of about 1.89 * 10^5 kg. Suppose the monument is lowered onto its side and dragged horizontally to a new location. An applied force of 7.6 * 10^5 N is exerted on the monument, so that its net acceleration is 0.11m/s^2. What is the magnitude of the frictional force? Can you show some work so that I can figure out how you did the problem?
Physics - 2 Answers
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1 :
Everything can be solved by the simple equation: F=ma Start with that. (I can solve this, but I would be doing your work for you, wouldn't I?)
2 :
For a body in constant acceleration, the sum of all forces is equal to m*a Prob 1) Convert the mass to weight: 9.5kg = 93.163 N Draw an x,y coordinate system along the incline, where the x coordinate is parallel to the slope and the y is perpendicular. SUM Fx = 93.163 * sin 30 - u*(80) = 1.64*9.5 where u is the coefficient of kinetic friction. u = (93.163*sin 30 - 1.64*9.5)/80 u = 0.3885 Prob 2) 1.89*10^5kg = 1853456.855412 N u = (7.6*10^5 - 0.11*1.89*10^5)/1853456.855412 u = 0.3988
