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Microchip Implant

Would you do this?. Microchip Implant. Review: Period (T), units - second. T (seconds) = Time # of Rotations. Little Bobby Bolo noticed his bolo swung around his head 2 times every 3.40 seconds. What period is the rotating bolo?

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Microchip Implant

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  1. Would you do this? Microchip Implant

  2. Review: Period (T), units - second T (seconds) = Time # of Rotations Little Bobby Bolo noticed his bolo swung around his head 2 times every 3.40 seconds. What period is the rotating bolo? T, (seconds) = Time # of Rotations

  3. Review: Frequency (f ), unit - Hertz f, (Hz) = # of Rotations Time Little Bobby Bolo noticed his bolo swung around his head 2 times every 3.40 seconds. What frequency is of the rotating bolo? f, (Hz) = # of Rotations Time T = 1.7 s

  4. Review: Velocityc f = .56 Hz

  5. Review: Accelerationc ac (m/s2) = v2 r Little Bobby Bolo noticed his bolo swung around his head with a velocity of 2.96 m/s. With a radius of .8 meters What is the centripetal acceleration of the rotating bolo? ac (m/s2) = v2 r

  6. Forcec • Centripetal force is a force that PULLS an object towards the center of rotation. • Many things can cause centripetal force • A string attached to a tetherball • The gravity of the Earth and the moon causing the moon to orbit the earth. • Friction on the tires of a car as it drives around a circular track ac = 10.95 m/s2

  7. Centripetal Force • An object moving in a circular motion is constantly accelerating. • In order to accelerate it must have a net force acting upon it. • Remember that F= ma • Therefore Fc=mac= mv2/r What happens if Fc is eliminated?

  8. Centripetal Force Fc (N) = mac = mv2 r Little Bobby Bolo noticed his .25 kg bolo swung around his head with an acceleration of 10.95 m/s2. What is the centripetal force of the rotating bolo? Fc (N) = mac Fc = 2.74 N

  9. Torque Notes Unit Eight Rotational Mechanics

  10. Rotational Inertia • Newton’s law of inertia states… • Also applies to rotational motion, • call this rotational inertia!!! • An object in rotation will continue to rotate unless another force acts on the object. Spinning Top

  11. Torque • A force exerted at a distance from the axis of rotation • To get an object to move (or) stop in a straight-line, a “force” must be applied. Newton’s 1st law • Thus, to get an object to start spinning, or to alter the rotation of a spinning object, a torque must be applied.

  12. Torque • The easiest way to think of torque is to consider a door. • When you open a door, where do you push? • If you exert a force at the hinge, the door will not move • If exert a force on the side of the door opposite the hinge, and to push or pull with a force perpendicular to the door.

  13. Force Causing torque Fulcrum

  14. Torque Torque = Fr • Note that the symbol for torque is the Greek letter tau. • Torque is the product of the distance from the point of rotation to where the force is applied multiplied by the force • Torque has units of Newton·meters

  15. Torque - Example • You use a wrench to loosen a bolt. It finally turns when you apply 250 N of force perpendicular to the wrench at a distance 0.3 m from the bolt. Calculate the torque. • Force = 250 N • Radius (distance from where force is applied) = 0.3 m Torque  (N-m) = Fr

  16. Torque - Example • The drain plug on a car’s engine is required to be tighten to a torque of 25 N•m. If you are using a 0.15 meter long wrench to tighten the plug, what is the minimum force you need to apply to loosen the plug?

  17. Torque - Example • A metal bar is used to pry a rock out of the ground by pivoting the bar under the rock and pushing down the on the other end. The end is pushed with a force of 200 N. If 2.2 m of the metal bar is extended out from under the rock, how much torque is being applied to the crowbar?

  18. Question…. • You are using the wrench below loosen bolts on your car tires. At what point would it be easier to loosen the bolt and why?

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