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What is the tangential acceleration of a point

  1. Mar 6, 2005 #1
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    1. A circular disk of radius 30 cm is rotating with an angular acceleration of 1 radian/ s2. What is the tangential acceleration of a point on the rim of the disk? What is its centripetal acceleration if the angular speed is 3 rev / s?

    2. A 980 Kg car traveling at 20 m/s rounds a curve of radius 40 m. What is the friction force that must act on the car to keep it in its circular path?

    3. An object with a mass of 100 Kg is dragged up an incline by applying a force F. The total distance moved along the incline is 200 m and the vertical height gained in moving this distance is 20 m. What is the magnitude of the force F if friction is negligible? (Assume g = 10 m/s2)

    4. What is the acceleration of an object that slides down an inclined plane that has a gradient of 1:4 (increases in height by 1 m when you travel along the plane 4 m) Ignore friction and assume g = 10 m/s2.

    5. A force of 5 N is applied to a door perpendicular to its face at a distance of 0.75 m from its hinge. What is the torque on the door about the hinge?

    6. The nut on a car wheel requires a torque of 75 N.m for opening it. A wrench 25 cm long is used to open the nut. What is the minimum force needed to open the nut?
     
  2. jcsd
  3. Mar 6, 2005 #2

    dextercioby

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    Well,you haven't read the stickied threads,haven't you...?So do it.

    Daniel.
     
  4. Mar 6, 2005 #3
    yeah G, give it a good shot at this problem then we're here to help.
     
  5. Mar 6, 2005 #4
    I am doing these problems just out of curiosity and I'm having trouble remembering the equation for #3. Is the equation mgcos(theta) or mgsin(theta)? IT's really troubling me.
     
  6. Mar 6, 2005 #5
    What equation? If you mean the force of gravity opposite to F, it should simplify to mg if theta = 90, so it must be sin.
     
  7. Mar 6, 2005 #6

    dextercioby

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    Is the velocity constant along the way...?If so,the the F should balance the tangential comonent of gravity perfectly.

    Daniel.
     
  8. Mar 6, 2005 #7
    so F=mgsin(theta) where m=100kg, g=10m/s^2, theta=5.73

    what if it asked for work? isn't that equation Fdcos(theta)?
     
  9. Mar 6, 2005 #8

    dextercioby

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    Why...?There's no friction.Again,work must be done against gravity.It's the force you computed times the distance the object moves (200m).

    Daniel.
     
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