Recent content by Warlic

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    Is it possible to use L= r x p to find angular momentum here

    I see, thank you. So if the object is not rotating, I can use L=MRV, where R is the distance to the center of mass of the object?
  2. W

    Is it possible to use L= r x p to find angular momentum here

    Homework Statement [/B]Homework Equations L = I ω L= r x p The Attempt at a Solution For b) My proffesor found the moment of inertia at the point at which the wheel touches the ground, and used the formula L = I ω What I don't understand is why can't one use L= r x p to solve the...
  3. W

    A plank that rests on top of two identical cylinders.

    Thank you, lol, seems ridiculous now, but I was thinking why isn't the car moving twice the speed of the center of mass of the wheels - didn't realize the car was only moving with the same speed as the axle and not the top of the wheels.
  4. W

    A plank that rests on top of two identical cylinders.

    Homework Statement Dont need to read the problem, just copied it on for the figure: So a plank rests on top of two identical cylindrical rollers - rolling without slipping both between cylinders and plank, and cylinders and surface. My book says that center of each roller moves forward only...
  5. W

    How much work does a crane and gravity do on a large box?

    Homework Statement [/B]Homework Equations E(p)=mgh W = Fs 3. The Attempt at a Solution The book says the crane does mgh amount of work, while gravity does -mgh. What I don't understand is, for the box to be lifted up, doesn't string tension force have to be bigger than gravity - or else it...
  6. W

    Questions about rolling and direction of static friction?

    Just one thing; "The wheels are thus subjected to two opposing torques, one from the axle" . How can there be a torque from the axle if the axle is right at the center of the wheel - because haven't we chosen the center of the wheel to be the origin point, and torque is T = r x F - isn't our...
  7. W

    Questions about rolling and direction of static friction?

    So in the first picture F(g) will reduce the angular acceleration but increase acceleration of center of mass? And what if we looked at the wheel of a car - would the motor be providing torque, acceleration of center of mass, or both?
  8. W

    Questions about rolling and direction of static friction?

    I have spent quite some time trying to get this, can someone please help me understand this? A plank is being pulled by a constant force F, it rests on top of two identitcal sylinders - there is rolling without slipping. What I don't understand is, why does F(p) - red arrow force, affect the...
  9. W

    In which direction does static friction point?

    Does the static friction have an x-component that is the centripetal force and force in the y-direction that is the tangential force - which keeps the child moving tangentially to the circle with 0.5m in radius?
  10. W

    In which direction does static friction point?

    As I see it; static friction is what provides the centripetal force, but does it do anything else? When the brother applies tangential force, what will happen with the static friction, because I assume it will start to provide less centripetal force because the tangential speed of the child...
  11. W

    Unsure about formula for kinetic energy

    It tells me there is zero potential energy at that point, everything is turned into kinetic energy?
  12. W

    Unsure about formula for kinetic energy

    Alright, thank you, I think I get the idea now
  13. W

    Unsure about formula for kinetic energy

    "the diameter of the ball is much smaller than the length of the pole." Why is this?
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