What is the significance of the sign of velocity in one dimensional motion

Aluminum–lithium (al-li) alloys have been developed by the aircraft industry to reduce the weight and improve the performance of its aircraft. a commercial aircraft skin material having a density of 2.47 g/cm3 is desired. compute the concentration of li (in wt%) that is required.

Which object forms when a supergiant runs out of fuel? a red giant a black hole a white dwarf a neutron star

How do you know when a chemical reaction has occurred