I'm not sure what your question is. But, the half life is the amount of time required for half the material to decay. For U238 this is 4.5 billion years, whilst for Fr-223 (Francium) its about 22 minutes. To calculate the time for something to decay you need to use the equation:
Mass (after time t) = Mass (initial) * (0.5)^(time/half life)
Hope this helps
4 fundamental forses are: strong, electro-magnetic, weak, gravity.
The strong force is the force which can hold nucleus together against enormous forces of repulsion of the protons is strong indeed. In comparasing to electro magnetic force, this force in not an inverse square and it has very short range.
The electro-magnetic force manifests itself as trough the forces between charges(Colubos law) and the magnetic force, both of which are summarized in the Lorentz force law. The electro-magnetic force holds atoms and moleculs together.
The weak force is a force between elementary particles certain processes that take place with low probability, as radio-active beta-decay and collisions between neutrinos and other particles.
The gravity force is the weakest of all 4 fundamental forces. It is the force of attraction between all masses in the universe, especially the attraction of the earth's mass for bodies near its suface. Newton's law of gravity states that gravitational force between two bodies is proportional to the product of their masses and inversely proportional to the square of the distance between them.
Car with a mass of 1210 kg moving at a velocity of 51 m/s.
2. What velocity must a 1340 kg car have in order to have the same momentum as a 2680 kg truck traveling at a velocity of 15 m/s to the west? 3.0 X 10^1 m/s to the west.
Hope i helped
Have a good day :)
Answer:
D. Both occur between objects independently whether they are in contact or not.
Explanation:
- The gravitational force is a force that is exerted between two (or more) objects having mass. This force is always attractive and its magnitude is given by
where G is the gravitational constant, m1 and m2 are the two masses, and r is the distance between the two masses.
- The electrical force is a force that is exerted between two (or more) objects having electrical charge. It can be either attractive or repulsive, depending on the sign of the two charges, and its magnitude is given by
where k is the Coulomb's constant, q1 and q2 are the two charges, and r the distance between the two charges.
Looking at both formulas, we see that the two forces are present even when the two objects are not in contact with each other (in fact, r can assume any value in the formula). They are said to be non-contact forces. Therefore, the correct option is
D. Both occur between objects independently whether they are in contact or not.
