- #1
JSGandora
- 95
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Consider a solid sphere and a cube of equal mass, both on a frictionless table. Now, you apply a force to both objects at the point of contact between the object and the table. Then the linear accelerations of both objects will be the same (since the same force is applied to the two objects of equal mass). Therefore, at some point in time, the velocities of both objects will be the same so their translational kinetic energies will also be the same.
Additionally, since you are applying a nonzero torque to the sphere, the sphere will rotate and therefore have a nonzero rotational kinetic energy at the same point in time. Therefore, the total kinetic energy of the sphere is greater than the total kinetic energy of the cube (since it does not rotate).
However, by the Work-Energy Theorem, shouldn't both objects have the same total kinetic energy since they both traverse the same distance (same accelerations) and both have the same force applied to them? Can someone explain this apparent paradox?
Additionally, since you are applying a nonzero torque to the sphere, the sphere will rotate and therefore have a nonzero rotational kinetic energy at the same point in time. Therefore, the total kinetic energy of the sphere is greater than the total kinetic energy of the cube (since it does not rotate).
However, by the Work-Energy Theorem, shouldn't both objects have the same total kinetic energy since they both traverse the same distance (same accelerations) and both have the same force applied to them? Can someone explain this apparent paradox?