physics

posted by .

A block of mass 0.78kg starts from rest at point A and slides down a frictionless hill of height h. At the bottom of the hill it slides across a horizontal piece of track where the coefficient of kinetic friction is 0.29. This section (from points B to C) is 4.08m in length. The block then enters a frictionless loop of radius r= 2.87m. Point D is the highest point in the loop. The loop has a total height of 2r. Note that the drawing below is not to scale.
a)What is the minimum speed of the block at point D that still allows the block to complete the loop without leaving the track?
b)What is the minimum kinetic energy for the block at point C in order to have enough speed at point D that the block will not leave the track?
c)What is the minimum kinetic energy for the block at point B in order to have enough speed at point D that the block will not leave the track?
d)What is the minimum height from which the block should start in order to have enough speed at point D that the block will not leave the track?

  • physics -

    (a) At the point D
    ma=mg
    mv²/r=mg
    v=sqrt(g•r)=sqrt(9.8•2.87)=5.3 m/s
    (b)
    KE(C)=PE+KE=
    =mg•2r+mv²/2=
    =m(2gr+5.3²/2)=54.8 J.

    (c)
    KE(B)=KE(C) + W(fr)=
    = KE(C) + μ•mg•s=
    =54.8+0.29•0.78•9.8•4.08=
    =63.8 J

    (d)
    PE1=KE(B)
    mgh= KE(B)
    h=KE(B)/mg=63.8/0.78•9.8 =8.35 m

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. physics

    Josh starts his sled at the top of a 2.0 m-high hill that has a constant slope of 25 degrees . After reaching the bottom, he slides across a horizontal patch of snow. The hill is frictionless, but the coefficient of kinetic friction …
  2. PHYSICS*****

    A block of mass m = 300 g is released from rest and slides down a frictionless track of height h = 59.4 cm. At the bottom of the track the block slides freely along a horizontal table until it hits a spring attached to a heavy, immovable …
  3. colledge physics

    A block of mass 0.78kg starts from rest at point A and slides down a frictionless hill of height h. At the bottom of the hill it slides across a horizontal piece of track where the coefficient of kinetic friction is 0.29. This section …
  4. physics

    I am having great difficulty with this question. A block is placed on a frictionless ramp at a height of 12.5 m above the ground. Starting from rest, the block slides down the ramp. At the bottom of the ramp, the block slides onto …
  5. Physics

    A block of mass m = 800 g is released from rest and slides down a frictionless track of height h = 57.0 cm. At the bottom of the track the block slides freely along a horizontal table until it hits a spring attached to a heavy, immovable …
  6. physics

    A block of mass m = 350 g is released from rest and slides down a frictionless track of height h = 58.9 cm. At the bottom of the track the block slides freely along a horizontal table until it hits a spring attached to a heavy, immovable …
  7. Physics

    A block is placed on a frictionless ramp at a height of 14.5 m above the ground. Starting from rest, the block slides down the ramp. At the bottom of the ramp, the block slides onto a frictionless horizontal track without slowing down.At …
  8. physics

    A child on a sled (total mass 41 kg) slides down a hill inclined at an angle θ = 22° at a constant speed 3.5 m/s. (a) How long does it take the child to travel 40 meters down the slope?
  9. Physics

    A block of mass 0.61kg starts from rest at point A and slides down a frictionless hill of height h. At the bottom of the hill it slides across a horizontal piece of track where the coefficient of kinetic friction is 0.40. This section …
  10. physics

    A block of mass 0.49kg starts from rest at point A and slides down a frictionless hill of height h. At the bottom of the hill it slides across a horizontal piece of track where the coefficient of kinetic friction is 0.28. This section …

More Similar Questions