- #1

OierL

- 5

- 0

## Homework Statement

Water is drawn from a well in a bucket tied to the end of a rope whose other end wraps around a cylinder of mass 50 kg and diameter 25 cm. As you turn this cylinder with a crank, the rope raises the bucket. If the mass of a bucket of water is 20 kg, what torque must you apply to the crank to raise the bucket of water at a constant speed?

Solution:

a. 2.5 N.m

b. 24 N.m

c. 80 N.m

d. 2400 N.m

e. 49 N.m

I don't know which one is the correct solution and why they give me the data of the weight of the cylinder.

## Homework Equations

∑F=m*a

∑M=F*r and ∑M=I*α

## The Attempt at a Solution

If we raise the bucket at a constant speed, ∑M=0

-m(bucket)*g + T=m*α*r=0 (constant speed) ⇒ T=m*g

∑M= (-T*R) + (τ)=0 (Being τ the torque I apply) ⇒ -(m*g*R) + τ=0 ⇒ τ= 20 * 9,8 * (0,25/2)

τ=24,5N*m