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You have a pumpkin of mass m and radius r. the pumpkin has the shape of a sphere, but it is not uniform inside so you do not know its moment of inertia. in order to determine the moment of inertia, you decide to roll the pumpkin down an incline that makes an angle θ with the horizontal. the pumpkin starts from rest and rolls without slipping. when it has descended a vertical height h, it has acquired a speed of v = √(5gh/4).

Theresa Perry

in Physics

1 answer

1 answer

Samantha Barber on November 27, 2018

As he is a descendant of a vertical height h, The lost Potential Energy = Mgh The cattle Kenetic Energy = (1/2)Mv^2; The rotation KE = (1/2)Jw^2 The angular velocity w = velocity/ Radius = v/R And Rotation KE = (1/2)Jw^2 = (1/2)J(v/R)^2; J is the moment of inertia Now Mgh = (1/2)Mv^2 + (1/2)J(v/R)^2 => 2gh/v^2 = 1 + (J/MR^2) As v = (5gh/4)^1/2, (J/MR^2) = 2gh/v^2 - 1 => (J/MR^2) = (8 gh/5gh) - 1 for (J/MR^2) = 3/5, and thus J = (3/5)MR^2.

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