Three blocks of weights W1 = 11 lb, W2 = 9 lb, and W3 = 10 lbare strung in the massless pulley system shown and released fromrest at initial time t0 at a distance H = 3 ft above the stopper asshown. The stopper has a hole in it which allows the narrower block3 to pass through. However, when block 2 contacts the stopper,block 2's motion stops, and only blocks 1 and 3 continue tomove.
a) What is the change in gravitational potential energy of thesystem from the initial time t0 to the time t1 immediately beforeblock 2 contacts the stopper?
HELP: Use kinematics to relate the positions and velocities of theblocks.
b)What is the kinetic energy of the system at time t1 immediatelybefore it contacts the stopper?
HELP: What is the initial kinetic energy of the system? HELP: Conserve energy from time t0 to time t1 just before block 2contacts the stopper.
c)What is the speed of block 2 at time t1 immediately before itcontacts the stopper?
HELP: This problem involves translation only, so you may usekinetic energy T=(mv^2) /2 for each block.
d)What is the kinetic energy of the system at time t2 just afterblock 2 contacts the stopper, i.e. the system in which blocks 1 and3 continue their motion without block 2?
HELP: Is (mechanical) energy conserved during the collision betweenblock 2 and the stopper from time t1 to time t2? HELP: No, it is not. Has the moving mass of the systemchanged? HELP: Have the speeds of the blocks that continue to movechanged?
e)When block 3 first comes to rest at time t3 (after passingthrough the stopper), how far will it be from where itstarted?
HELP: Conserve energy from the time immediately after the collisionbetween block 2 and the stopper to the time when blocks 1 and 3stop, i.e. from time t2 to time t3. HELP: Carefully consider for what the question is asking.
