Term
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Definition
| when an object spins on its axis in rotational motion |
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Term
| What is angular displacement? What is its symbol? What units is it measured in? |
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Definition
| the change in the angle as an object rotates; theta; revolutions, degrees, radians |
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Term
| What is the angular displacement of a second hand on a clock in ten minutes? |
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Definition
| 10 revolutions; 2 pi; 3600 degrees |
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Term
| What is angular velocity? What is the symbol? What units is it measured in? |
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Definition
| the rate of rotation (rev/sec); omega; change in angular displacemnt/change in time; rev/sec or rad/sec or degrees/sec |
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Term
| What is the angular velocity in radians of a tops that turns 100 times in 5 seconds? |
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Definition
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Term
| What is tangential speed? How does the tangential speed vary across a rotating disk? How do you convert from angular velocity to tangential velocity? |
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Definition
| the actual meters/sec it is traveling; as you move outward, the faster you go; V=r(omega) and omega must be in radians |
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Term
| An object has an angular velocity of 50 radians/sec. At a distance of .5m from the axis of rotation what is the tangential speed? |
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Definition
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Term
| What is angular acceleration? What is the symbol? What are the units? |
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Definition
| the rate of change of angular velocity; aplpha=change in angular velocity/change in time; rev/s squared |
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Term
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Definition
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Term
| An object spinning at 1000 rpm slows to a stop in 10 seconds, what is the angular acceleration? |
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Definition
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Term
| What causes rotation? What is torque? |
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Definition
| torque; rotational effect caused by parallel forces |
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Term
| How do you calculate torque? |
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Definition
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Term
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Definition
| perpendicular length from the pivot point to the force |
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Term
| What happens to the gorque if the line of the force passes through the pivot point? |
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Definition
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Term
| How do you calculate torque if the force is an angle to the object? |
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Definition
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Term
| What is rotational inertia or the moment of inertia? |
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Definition
| when an object starts rotating, it wants to keep rotating; rotational inertia = moment of inertia |
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Term
| What deteremines how much rotational inertia something has? |
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Definition
| the distribution of the mass; the big wheel has more rotational inertia than a small wheel |
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Term
| What is the center of gravity (mass)? |
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Definition
| the point at which you draw your force vector down; where the force of gravity acts |
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Term
| when will toppling occur? |
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Definition
| when the center of gravity is not over the base of support |
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Term
| What are the 3 types of equlibrium? |
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Definition
| stable, unstable, equilibrium |
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Term
| What are the two conditions of equlibrium? |
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Definition
| translational and rotational; translational--Fup=Fdown; rotational--CW torque=CCW torque; both of these conditions must be met in order to be in equlibrium |
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Term
| review all problems: seesaw, torque, equlibriant, bridge, angular displacement, velocity, acceleration, etc |
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Definition
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Term
| What is the angular displacement of a second hand in 1.5 minutes? |
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Definition
| 1.5 revolutions; 540 degrees; 3 pi radians |
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Term
| What is the angular displacement of a second hand in five minutes? |
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Definition
| 5 revolutions, 1800 degrees; 10 pi radians |
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Term
| Which part of the earth's surface has the greatest rotational speed about the earth's axis? |
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Definition
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Term
| Which part of the earth's surface has the greatest linear speed relative to the axis? |
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Definition
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Term
| On a particular merry g round, the horses along the outer rail are located three times farther from the axis of rotation than the horses along the inner rail. If a boy sitting on a horse near the inner rail has a rotation speed of 4 rpm and a tangential pseed of 2 m/s, what will be the rotational speed and tangential speed of his sister who is sitting on a horse along the outer rail? |
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Definition
| 4 rpm--rotational; 6 m/s--linear |
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Term
| A wirte with 4 light bulbs is twirled ina circle. The bulbs are numbered 1-4, with four being on the outside of the circle and 1 being towards the center. Which of the bulbs have the greatest rotational speed? Which of the bulbs has the greatest tangential speed? |
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Definition
| they have the same rotational speed; bulb 4 has the greatest tangential speed |
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Term
| A fan rotating at 200 rpms takes 15 seconds to stop turning when it is turned off, what is the angular acceleration? |
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Definition
| 0-200/15=-13.3 rev/min/sec |
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Term
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Definition
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Term
| What are the charateristics of torque? |
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Definition
| different from force, causes rotation, produced when a force is applied parallel to another force, measured in meter newtons |
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Term
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Definition
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Term
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Definition
| perpendicular distance from F to pivot point |
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Term
| What when force is applied further from pivot point? |
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Definition
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Term
| How do you calculate the torque if the force is at an angle? |
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Definition
| find the y component and multiply by the l |
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Term
| the more mass, the more____. |
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Definition
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Term
| What are the characteristics of rotational inertia? |
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Definition
| varies with the radius and distribution of mass; as the radius increases so does the intertia; as the distribution is further ot the inertia increases |
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Term
| Why does a tight rope walker carry a long pole? |
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Definition
| it gives him a vetter moement of inertia so he doesnt fall |
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Term
| Why do we bend our knees more when we run? |
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Definition
| it reduces our moment of inertia |
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Term
| Where is the center of gravity of a bicycle tire located? |
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Definition
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Term
| What is unstable equilibrium? |
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Definition
| the center of gravity goes lower and is easy to turn over |
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Term
| What is stable equlibrium? |
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Definition
| the center of gravity must go up; hard to turn over |
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Term
| What is neutral equlibrium? |
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Definition
| center of gravity stays in the same place (ball) |
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Term
| When you balance an object, are you balancing weight or torque? |
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Definition
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