PreLab and Lab _Constant Acceleration(1)

PreLab and Lab _Constant Acceleration(1) - Name Section...

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Name: _____________________ Section: _________________ Date: ______________ Pre-Lab: Constant Acceleration/ Newton’s Second Law 1. Newton’s Second Law indicated that when a net force acts on an object, it must accelerate. Does this mean that when two or more forces are applied to an object simultaneously, it must accelerate? (2points) Newton’s second law applies where there is net force acting on an object. If the net force is zero, then there will be no acceleration in the motion of the object involved. Therefore, it is not a must an object accelerates when two or more forces are applied. All what matters is the presence of a net force. 2. An object of mass m1=5.00 kg placed on a frictionless, horizontal table is connected to a string that passes over a pulley and then is fastened to a hanging object of mass m2 – 9.00 kg as shown in the figure. (6 points) a) Draw a free body diagrams for both objects; b) Find the magnitude of the acceleration of the objects; The string does not stretch therefore; both the object and mass have the same magnitude of acceleration. There is no friction in this case, hence
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Unformatted text preview: Using F = ma on both objects, Equation (2) becomes T = M 1 a and Equation (3) becomes m 2 g − T = m 2 a Combining the two equations by substituting T in equation (3) 1 It becomes m 2 g − M 1 a = m 2 a Further; m 2 g = (M 1 + m 2 ) a a = m 2 g / (M 1 + m 2 ) = (9.00 kg · 9.80 m/s 2 )/ (5.00 kg + 9.00 kg) =88.2/14= 6.30 m/s 2 c) Find the tension in the string; From eq. (2) T = M 1 a, but a = m 2 g / (M 1 + m 2 ) Hence T= (M 1 m 2 g)/ (M 1 + m 2 ) = (5.00 kg · 9.00 kg · 9.80 m/s 2 )/ (5.00 kg + 9.00 kg) = (441/14) N =31.5 N 3. Use the (velocity vs time) graph below to answer the following three questions: (2points) a) What is acceleration of an object and its error according to the graph? 4.393+/-0.3126m/s 2 b) What physics quantity does the slope of the velocity vs time graph presents? It presents acceleration c) If the graph was generated using the set-up of Lab “Newton’s Second Law” was the cart moving toward or away from the motion sensor? The cart was moving away from the motion sensor. It is because the graph is on the positive side of x-axis. 2...
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  • Spring '15
  • Force, net force, Newton’s Second Law

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