# lab report physics 4.docx - LINEAR MOTION OBJECTIVE To use...

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LINEAR MOTION OBJECTIVETo use linear air track to investigate Newton’s Second Law of MotionTHEORYNewton’s equation of motion for a point of mass mto which a force Fis applied is given by the following:F = maAs indicated by Figure 1, when m2 is released, both objects will accelerate. Two masses will haveaccelerations, a of the same magnitude because they are connected as a single system by an unstretchable, massless string. An analysis of the motion of the system assuming that Newton’s Law of Motion are correct is set out belowN TTW2 = m2gW1 =m1gFigure 4.1 : Free body diagrams of the forces acting on (a) m2and (b) m1As shown in Figure 2 (a), there are three forces acting on m2 ; the force from the contact of the frictionless surface pushing up on m2labelled T. The contact (normal) force and gravitational force cancel each other, meaning the total force acting on along vertical direction on m2 is equal to zero. This leaves the tension in the string as the total force acting on m2 . Newton’s Second Law said that m2will accelerate and give the equation:T = m2aFigure 2 (b) shows that there are only two forces acting on m1namely the gravitational force, W =m1g in downward direction and the tension that pulls m1 upward. By using Newton’s second law;Ftotal =T m1g = -m1a
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