You are to design a rotating cylindrical axle to lift 800 N buckets of cement from the ground to a rooftop 78.0 m above the ground. The buckets will be attached to a hook on the free end of a cable that wraps around the rim of the axle; as the axle turns, the buckets will rise.

What should the diameter of the axle be in order to raise the buckets at a steady 2.00 cm/s when it is turning at 7.5 rpm?

Respuesta :

Answer:

5.09 cm

Explanation:

using the formula

V = rω where r is radius and ω is the angular speed and V is the speed

ω = 7. 5 rpm = 7.5 × 2πrad / 60 seconds = 0.7855 rad s⁻¹ since one revolution = 2π and 1 minutes = 60 seconds

2.00 cm/s =r ×0.7855 rad s⁻¹

r = 2.00 cm/s / 0.7855 rad s⁻¹ = 2.546 cm

d = 2r =2 × 2.546 cm = 5.09 cm

the relations between the angular and linear variables allows to find the result for the diameter of the cylinder is:

  • The diameter is: d = 5.09 cm

Kinematics studies the movement of bodies, the movement being able to be linear, rotational or a combination of the two.

The linear and rotational movements are related, by the expressions.

          x = θ r

          v = w r

          a = α r

Where x, v and a are the linear variables and  θ, w and α the angular variables, r is the radius vector. For this relationship to be true, the angles must be measured in radians.

They indicate the angular speed of the cylinder is w = 7.5 rpm, reduce it to radians per second.

          [tex]w = 7.5 \frac{rev}{min} (\frac{2\pi rad}{1 rev}) ( \frac{1 min}{60 s}) \\ w = 0.7854 \frac{rad}{s}[/tex]

we substitute in the relationship between the angular and linear variable.

           v = w r

They indicate that the linear velocity is constant v = 2.0 cm/s = 2.0 10⁻²m/s.

           [tex]r = \frac{v}{w}[/tex]

Let's calculate.

           [tex]r = \frac{2 \ 10^{-2}}{0.7854}[/tex]  

           r = 2.546 10⁻²  m = 2.546 cm

The diameter is twice the radius.

          d = 2 r

          d = 2 2.546 cm

          d = 5.09 cm.

In conclusion using the relationships between the angular and linear variables we can find the result for the diameter of the cylinder is:

  • The diameter is: d = 5.09 cm

Learn more about the relationship between angular and linear variables here: brainly.com/question/14312001