C. when you can't achieve your goal due to events beyond your control
1. <span>Molecules rearrange and form new molecules - exchange (they exchange some material in order to produce new things)
2. </span><span>simultaneous decomposition and synthesis - reversible (it can go back)
3. </span><span>bonds broken and elements released - decomposition
4. </span><span>molecules formed from components - synthesis (these components merge and create molecules)</span>
Most stars take millions of years to die. When a star like the Sun has burned all of its hydrogen fuel, it expands to become a red giant then when it fully runs out it then dies
Rolling friction is considerably less than sliding friction as there is no work done against the body that is rolling by the force of friction. For a body to start rolling a small amount of friction is required at the point where it rests on the other surface, else it would slide instead of roll.