Two identical twins hold on to a rope, one at each end, on a smooth, frictionless ice surface. They skate in a circle about the center of the rope (the center of mass of the two-body system) and perpendicular to the ice. The mass of each twin is 85.0 kg. The rope of negligible mass is 3.0 m long and they move at a speed of 5.00 m/s. (a) What is the magnitude of the angular momentum of the system comprised of the two twins? kg · m2/s (b) They now pull on the rope and move closer to each other so that the rope between them is now half as long. Determine the speed with which they move now. m/s (c) The two twins have to do work in order to move closer to each other. How much work did they do? J

Answer with Explanation:

We are given that

Mass of each twin=85 kg

Length of rope=l=3 m

Initial speed,u=5 m/s

a.Angular momentum of the system=

Using the formula

b.According to law of conservation of angular momentum

c.According to work energy theorem

Work done by twins=Change in kinetic energy

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.