Answer:
a quantitative observation because it includes numerical data
Electromagnetic waves can travel in vaccum but mechanical wave does not
Correct ones are
- Technical improvements that have made alternative energy sources more practical to use
- Increase in concern for environment.
why?
Fossil fuels are hydrocarbons
- Hydrocarbons on burning with oxygen releases harmful carbon dioxide .
Answer:
Option C
100 J
Explanation:
Kinetic energy, KE is given by
where m is the mass and v is the velocity
Substituting 50 Kg for mass, m and 2 m/s for velocity v then we obtain

Therefore, the child's kinetic energy is equivalent to 100 J
Answer:
The electromagnetic force
Explanation:
The electromagnetic force is one of the four fundamental forces of nature. Namely, they are:
- Electromagnetic force: it is the force exerted between electrically charged particles (and between magnetic fields). The force can be either attractive (if the two charges have opposite signs) or repulsive (if the two charges have same sign), and it acts over an infinite range.
- Gravitational force: it is the force exerted between objects with mass. It is always attractive, and it also has an infinite range of action. It is the weakest of the four fundamental forces.
- Strong nuclear force: it is the force that acts between protons and neutrons inside the nucleus, and it is responsible for keeping the nucleus together and preventing it from breaking apart (due to the electrostatic repulsion between protons)
- Weak nuclear force: it is the force responsible for certains nuclear decays, such as the beta decay, in which a neutron turns into a proton, emitting an electron and an antineutrino.