Friday, September 9, 2011

What is the speed of the plane and the tension in the string?

A model airplane of mass 1.2 kg is attached to a horizontal string and flies in a horizontal circle of radius 5.3 m, making 1.6 revolutions every 6 s. (The weight of the plane is balanced by the upward “lift” force of the air on the wings of the plane.) The acceleration due to the gravity is 9.81m/s2. Find the speed of the plane.





Answer in units of m/s.





Also Find the tension in the string.





Answer in units of N.|||The speed v = r*ω where ω = 1.6rev*2π/6s = 1.68rad/s





So v = 5.3m*1.68rad/s = 8.88m/s








Now from F = m*a we have T = m*v^2/r = 1.2kg*(8.88m/s)^2/5.3m = 17.9N

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