- #1

- 3

- 0

Relevant equations (I think...):

I=1/2MR^2

FR=Iα

α=a/R

So far, I have:

FR=Iα

FR=1/2MR^2(a/R)

F=1/2Ma

a=2*F/M=3.33333 m/s^2

and then,

v^2=2*a*6m, since initial velocity is 0.

v=7.26 m/s

But this is wrong, and I'm not sure why. Please help!

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In summary, a solid uniform disk of mass 19.0 kg and radius 70.0 cm is at rest on a frictionless surface. A string is wrapped around the rim of the disk and a constant force of 35.0 N is applied to the string. When the disk has moved a distance of 6 m, the speed of the center of mass is found to be 5.1 m/s. This is calculated using Newton's Second Law, taking into account that only the force applied by the string contributes to the acceleration of the disk.

- #1

- 3

- 0

Relevant equations (I think...):

I=1/2MR^2

FR=Iα

α=a/R

So far, I have:

FR=Iα

FR=1/2MR^2(a/R)

F=1/2Ma

a=2*F/M=3.33333 m/s^2

and then,

v^2=2*a*6m, since initial velocity is 0.

v=7.26 m/s

But this is wrong, and I'm not sure why. Please help!

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- #2

Mentor

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- 2,931

- #3

- 3

- 0

I'm so frustrated :)

- #4

Mentor

- 20,985

- 2,931

atlarge said:

I'm so frustrated :)

mg and the normal force are equal and opposite, so their contribution vanishes. You only have to deal with the force applied via the string.

- #5

- 3

- 0

Answer is:

F=ma

35N=(21kg)a

a=1.667 m/s^2

v^2=0 + 2(1.667)(7.9), 0 being the initial velocity

v=5.1 m/s

The center of mass of a spinning disk is the point at which the disk's mass can be considered to be concentrated. It is the point around which the disk's mass is evenly distributed, and it remains fixed even as the disk spins.

The velocity of the center of mass of a spinning disk can be calculated using the formula v = ωr, where v is the velocity, ω is the angular velocity, and r is the distance from the center of mass to the axis of rotation.

The velocity of the center of mass remains constant as the spinning disk rotates, as long as there are no external forces acting on the disk. This is due to the conservation of angular momentum.

The velocity of the center of mass of a spinning disk can be affected by the mass distribution of the disk, the angular velocity of the disk, and any external forces acting on the disk, such as friction or air resistance.

The velocity of the center of mass of a spinning disk is directly proportional to its rotational kinetic energy. This means that as the velocity increases, so does the rotational kinetic energy, and vice versa.

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