If we multiply all the design dimensions of an object by a scalin...

Question

If we multiply all the design dimensions of an object by a scaling factor f, its volume and mass will be multiplied by f^3. (b) If a 1/48 scale model has a rotational kinetic energy of 2.5 J, what will be the kinetic energy for the full-scale object of the same material rotating at the same angular velocity?

Accepted Answer

Hello. So in this problem you make a corner weld between two unicorn rods of mass, one kg length, three m each. In this situation the two rods are perpendicular to each other, determine the moment of inertia about an axis perpendicular to the plane of the system and passing through the welding point. So schematically we have one rod, we have another rod perpendicular to each other. Both passes one kg both with lengths you're welded and you want to find one of inertia about this corner passing through the plane of the system. So we recall since these are rods rotating about one of the sides. The equation for the moment of inertia of a Rod is equal to 1/ m. elsewhere. So for one of these rods, moment of inertia would simply just be one third times one kg Times three m squared. Which gives us cancel out this cancels out three kg times meters squared. Now we notice that there are two rods in the plane of this system and they're both rotating with three kg times meters squared in their moments of inertia. So I total of the system will be two times I broad which will be equal to six kg times meters. Sport, if this doesn't answer choice C. I hope this up have a great day

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