Using the equation of motion, v = u + at, where u is the initial velocity, a is the acceleration due to gravity (-9.8 m/s^2), and t is the time, we can calculate the velocity after 2 seconds: v = 10 m/s + (-9.8 m/s^2) * 2 s = -20 m/s.

Average speed is calculated by dividing the total distance traveled by the total time taken. In this case, the average speed is 100 km / 2 h = 50 km/h.

According to Newton's second law of motion, F = ma, where F is the force applied, m is the mass of the object, and a is the acceleration. Therefore, the acceleration of the object is 10 N / 2 kg = 5 m/s^2.

When a light beam travels from a less dense medium to a denser medium, its speed decreases. This is because the denser medium offers more resistance to the light waves, causing them to slow down.

From the equation, we can see that the period of oscillation is proportional to the square root of the length of the pendulum. Therefore, if the length is doubled, the period will also double.

Using the thin lens equation, (\frac{1}{f} = \frac{1}{u} + \frac{1}{v}), where f is the focal length, u is the object distance, and v is the image distance, we can calculate the image distance: (\frac{1}{10 cm} = \frac{1}{20 cm} + \frac{1}{v}). Solving for v, we get v = 30 cm.

A scalar quantity is a physical quantity that has only magnitude and no direction. Temperature is an example of a scalar quantity because it has only a magnitude (in degrees Celsius, Fahrenheit, or Kelvin) and no direction.

A vector quantity is a physical quantity that has both magnitude and direction. Velocity is an example of a vector quantity because it has both a magnitude (speed) and a direction (the direction in which the object is moving).

The SI unit of electric charge is the coulomb (C). It is named after the French physicist Charles-Augustin de Coulomb, who made significant contributions to the study of electricity and magnetism.

In a simple circuit, the relationship between electric current and voltage is described by Ohm's law: (I = V/R), where I is the current, V is the voltage, and R is the resistance. This means that current is directly proportional to voltage, as long as the resistance remains constant.

The SI unit of energy is the joule (J). It is named after the English physicist James Prescott Joule, who made significant contributions to the study of energy and heat.

Energy and power are related by the equation (E = Pt), where E is energy, P is power, and t is time. This means that energy is directly proportional to power, as long as the time interval is constant.

The SI unit of frequency is the hertz (Hz). It is named after the German physicist Heinrich Hertz, who made significant contributions to the study of electromagnetic waves.

Frequency and wavelength are related by the equation (f = c/\lambda), where f is frequency, c is the speed of light, and \lambda\ is wavelength. This means that frequency is inversely proportional to wavelength, as long as the speed of light remains constant.

The SI unit of mass is the kilogram (kg). It is defined as the mass of the International Prototype Kilogram, a cylinder of platinum-iridium alloy kept at the International Bureau of Weights and Measures in France.