A small block on a frictionless, horizontal surface has a mass of 0.0245 kg. It
ID: 2264723 • Letter: A
Question
A small block on a frictionless, horizontal surface has a mass of 0.0245 kg. It is attached to a massless cord passing through a hole in the surface (see figure below). The block is originally revolving at a distance of 0.350 m from the hole with an angular speed of 1.90 rad/s. The cord is then pulled from below, shortening the radius of the circle in which the block revolves to 0.175 m. Model the block as a particle.
A small block on a frictionless, horizontal surface has a mass of 0.0245 kg. It is attached to a massless cord passing through a hole in the surface (see figure below). The block is originally revolving at a distance of 0.350 m from the hole with an angular speed of 1.90 rad/s. The cord is then pulled from below, shortening the radius of the circle in which the block revolves to 0.175 m. Model the block as a particle. Is angular momentum of the block conserved? Why or why not? What is the new angular speed? rad/s Find the change in kinetic energy of the block. L How much work was done in pulling the cord? JExplanation / Answer
yes the angular momentum will be conserved because the only force acting is in radial direction and hence it will not have any component in tangential direction son no torque will act
since the angular momentum is conserved
initial angular momentum = final angular momentum
initial moment of Inertia = 0.0245*0.350^2 = 0.0030
new moment of inertia = 0.0245*0.175^2 = 0.00075