Correct A small block on a frictionless, horizontal surface has a mass of 2.40x1
ID: 1792248 • Letter: C
Question
Correct A small block on a frictionless, horizontal surface has a mass of 2.40x10-2 kg. It is attached to a massless cord passing through a hole in the surface (Figure 1) The block is originally revolving at a distance of 0.300 mm from the hole with an angular speed of 2.41 rad/s . The cord is then pulled from below, shortening the radius of the circle in which the block revolves to 0.150 m. Model the block as a particle Part C Find the change in kinetic energy of the block. Express your answer with the appropriate units Submit My Answers Give Up Figure 1 of 1 Incorrect; Try Again; 2 attempts remaining Part D How much work was done in pulling the cord? Express your answer with the appropriate units W-Value Units Submit My Answers Give UpExplanation / Answer
C] Angular momentum = mvr is conserved,
radius becomes half, velocity v becomes double = 2*2.41*0.3 = 1.446 m/s
delta K = 0.5 mv^2 - 0.5mu^2
= 0.5*2.4e-2*(1.446^2- (2.41*0.3)^2)
= 0.0188 J answer
partD] work done = chamge in KE = 0.0188 J answer