Two similar spheres, each of mass m and radius r, are in contact. One sphere is moved away through a distance 3r. What is the ratio between the original gravitational attraction between the spheres and the final gravitational attraction between them?

What happens to atoms and chemical bonds during a reaction?

The bar of prob. 5/82 is repeated here. the ends of the 0.4-m bar remain in contact with their re- spective support surfaces. end b has a velocity of 0.5 m/s and an acceleration of 0.3 m/s2 in the di- rections shown. determine the angular accelera- tion of the bar and the acceleration of end a.

What is the difference between mass density and weight density?