First half:
50 km at 50 km/hr ... 1 hour
Second half:
50 km at 100 km/hr ... 1/2 hour
Total distance = 100 km
Total time = 1.5 hours
Average speed = (100 km) / (1.5 hrs)
Average speed = 66 and 2/3 km/hr
Average velocity = 66 and 2/3 km/hr East
1. because they have the same numbers of protons and electrons.
2. by the number of its protons and neutrons
3. yes, because the isotopes of an element also have the same number of electrons.
Explanation:
In physical sciences, mechanical energy is the sum of potential energy and kinetic energy. It is the macroscopic energy associated with a system. The principle of conservation of mechanical energy states that if an isolated system is subject only to conservative forces, then the mechanical energy is constant. If an object moves in the opposite direction of a conservative net force, the potential energy will increase; and if the speed (not the velocity) of the object changes, the kinetic energy of the object also changes. In all real systems, however, nonconservative forces, such as frictional forces, will be present, but if they are of negligible magnitude, the mechanical energy changes little and its conservation is a useful approximation. In elastic collisions, the kinetic energy is conserved, but in inelastic collisions some mechanical energy may be converted into thermal energy. The equivalence between lost mechanical energy (dissipation) and an increase in temperature was discovered by James Prescott Joule.
Answer:
william h. seward secured the purchase of alaska from:
Explanation:
<span>The American Southwest and northeastern Africa are the two sunniest regions of the world, with the U.S. city of Yuma, Arizona, taking the crown as the sunniest place on Earth. Yuma, located where the state borders both California and Mexico, receives more than 4,000 sunlight hours per year and averages 11 sunny hours per day over the course of the year. Following closely behind Yuma is another U.S. city -- Phoenix -- which receives an average of 3,872 sunlight hours a year. The third sunniest spot on Earth is Aswan, Egypt, which has an average of 3,863 sunlight hours every year and averages 10.6 sunny hours per day.</span>
