If the point B was initially at the same level as the center of the pulley C, what is the direction of the velocity of point B after the pulley at A has undergone 2 revolutions? Give this in degrees from the horizontal (positive in the counterclockwise direction, negative in the clockwise direction)

θ = 720º

Explanation:

Let's use the rotational kinematics relations for this exercise, remember that all angles must be given in radians.

Let's reduce the magnitudes to the SI system

         θ = 2 rev (2π rad / 1 rev) = 4π rad

we assume that the pulley has a radius r

linear and angular coordinates are related

         y = θ r

let's calculate

         y = 4π r

to convert the distance in angles to radians

        θ = y / r

        θ = 4π

let's change this angle to degrees

        π rad = 180º

         θ = 4π rad (180º /π rad)

         θ = 720º

80cm/s.

24cm/s.

53.3cm/s.