In 1999 scientists discovered a new class of black holes with masses 100 to 10000 times the mass of our sun but occupyin less space than our moon. suppose that one of these black holes has a mass of 1 x 103 suns and a radius equal to one half the radius of our moon. The radius of our sun is 7.0 x 10^5 km with an average density of 1.4 x 10^3 kgm3. The diameter of the moon is 2.16 x 10^3 miles. What is the density of the black holes?

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.

If forces acting on an object are unbalanced. true or false

Give an example of a collision in real life. use the law of conservation of energy to describe the transfer of momentum. be sure and discuss the momentum before and after the collision occurs. you will need at least 3 sentences to thoroughly answer this question.