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Rotational Inertia ( I ): A measure of an object’s reluctance to changing its rotational motion. Objects with their mass concentrated closer to their centre of mass and rotation will have a rotational inertia than objects with their mass distributed farther out towards their edges.
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Rotational Inertia (I): A measure of an object’s reluctance to changing its rotational motion Objects with their mass concentrated closer to their centre of mass and rotation will have a rotational inertia than objects with their mass distributed farther out towards their edges. Therefore, objects with their mass concentrated closer to their centre of mass & rotation are to accelerate.
Rotational Inertia (I): A measure of an object’s reluctance to changing its rotational motion You already know this instinctively…. [Video Clip from beginning of class] Philippe Petit, the tightrope walker who walked between the Twin Towers in 1974, is the subject of the documentary, Man On Wire
Rotational Inertia (I): A measure of an object’s reluctance to changing its rotational motion If we get these two discs spinning, which one would have more Kinetic Energy? Justify your choice.
Rotational Kinetic Energy (Er): A measure of an object’s energy due to its rotational motion If we get these two spinning, which one would have more Kinetic Energy? Justify your choice. What else would be a factor? Can you guess what the formula might be?
Rotational Kinetic Energy (Er): A measure of an object’s energy due to its rotational motion Er= ½ I ω2
Rotational Kinetic Energy (Er): A measure of an object’s energy due to its rotational motion Er= ½ I ω2 An argument arose between two teachers: Does the speed of an object at the bottom of a ramp depend on its mass if it is released from rest at the top of the ramp? Ms Calver says “no” Mr X says “yes” Of course Ms Calver is correct – can you prove it?
Rotational Kinetic Energy (Er): A measure of an object’s energy due to its rotational motion Er= ½ I ω2 Does the speed of an object at the bottom of a ramp depend on its mass if it is released from rest at the top of the ramp?
Rotational Kinetic Energy (Er): A measure of an object’s energy due to its rotational motion Er= ½ I ω2 Does the speed of an object at the bottom of a ramp depend on its mass if it is released from rest at the top of the ramp?
Rotational Kinetic Energy (Er): A measure of an object’s energy due to its rotational motion Er= ½ I ω2 Does the speed of an object at the bottom of a ramp depend on its mass if it is released from rest at the top of the ramp? Two 0.24 m radius pingpong balls, an empty one with a mass of 0.004 kg and one filled with sand so that its mass is 0.048 kg, were released from a height of 0.16 m. What is the difference in linear velocity at the bottom. Ihollow-sphere = ⅔mr2 Isolid-sphere = ⅖mr2
Rotational Kinetic Energy (Er): A measure of an object’s energy due to its rotational motion Er= ½ I ω2 Two 0.24 m radius pingpong balls, an empty one with a mass of 0.004 kg and one filled with sand so that its mass is 0.048 kg, were released from a height of 0.16 m. What is the difference between their linear velocity at the bottom? Ihollow-sphere = ⅔mr2 Isolid-sphere = ⅖mr2