Physics Test-2

Given,

Mass (m) = 5 kg

Coefficient of friction (μ) = 0.3

g = 10 m/s2

Free body diagram of the given condition,

In vertical direction forces are balanced.

∴ \(N = mg\)

The friction force is calculated by,

\(F = μ N =  μ mg\)

∴ \(F = 0.3 × 5 × 10 = 15\) N

We know that \(\mathrm{J}=\frac{\mathrm{I}}{\mathrm{A}}\) and \(\mathrm{E}=\frac{\mathrm{I}}{\sigma \mathrm{A}}\);

\(\therefore \mathrm{E}=\frac{\mathrm{J}}{\sigma}=\rho \mathrm{J}=\mathrm{kJ}\)

The Parsec (symbol pc) is an astronomical unit of length. It grows to be around 30 trillion kilometers. Parsec is used in astronomy. Its length is based on the trigonometric angle, an ancient method of measuring distances between stars.

The centre of mass from the base of hemisphere is given as, C.O.M \(=\frac{3}{8} \mathrm{R}\)
By substituting the value of radius in the above equation we get, C.O.M \(=\frac{3}{8} \times 16=6 \mathrm{~cm}\)

Brewster Law \(\tan i _{ p }=\mu\) but \(\mu \propto \frac{1}{\lambda}\)

\(\therefore \tan i _{ p } \propto \frac{1}{\lambda}\)

where \(i _{ p }, \mu\) and \(\lambda\) are angle of polarisation (incidence), refractive index of material and wavelength of light respectively

Let a body of mass ' \(\mathrm{m}^{\prime}\) placed at a height \(^{\prime} \mathrm{h}^{\prime}\) above the ground, start falling down from rest. '

When the body falls from a height \(\mathrm{h}\) to \(\frac{h}{2}\), the potential energy is given as \(\frac{\mathrm{mgh}}{2}\).

The body covers the distance \(\frac{\mathrm{h}}{2}\) with a velocity \(\mathrm{v}\). We make use of the third equation of motion to obtain velocity of the body.

\(\mathrm{v}^{2}-\mathrm{u}^{2}=2 \mathrm{a} \mathrm{S}\)

Here, \(u=0, a=g\) and \(S=\frac{h}{2}\)

\(\mathrm{v}^{2}-0=\frac{2 \mathrm{gh}}{2}\), that is \(\mathrm{v}^{2}=\mathrm{gh}\)

Kinetic energy \(=\frac{1}{2} \mathrm{mv}^{2}\)

That is, K.E \(=\frac{\mathrm{mgh}}{2}\)

Therefore, at height \(\frac{h}{2}\) the energy possessed is half potential energy and half the kinetic energy.

The buoyant force depends on the volume of the liquid displaced.

The buoyant force depends directly upon:

• The volume of the fluid is displaced.
• The density of the fluid in which the body is immersed.
• Acceleration due to gravity at the place.

Kirchhoff's Law describes the enthalpy of a reaction's variation with temperature changes. In general, enthalpy of any substance increases with temperature, which means both the products and the reactants' enthalpies increase. The overall enthalpy of the reaction will change if the increase in the enthalpy of products and reactants is different.

At constant pressure, the heat capacity is equal to change in enthalpy divided by the change in temperature.

\(c_{p}=\frac{\Delta H}{\Delta T}\)

Therefore, if the heat capacities do not vary with temperature then the change in enthalpy is a function of the difference in temperature and heat capacities. The amount that the enthalpy changes by is proportional to the product of temperature change and change in heat capacities of products and reactants.

The Reynolds number is the ratio of inertial forces to viscous forces. The Reynolds number is a dimensionless number used to categorize the fluids systems in which the effect of viscosity is important in controlling the velocities or the flow pattern of a fluid.

According to Rutherford's model, electrons move around the nucleus in an atom in certain circular orbits. But according to the classical theory of electrodynamics, a moving electron, will always emit energy. Thereby the electron loses energy and ultimately falls into the nucleus. Therefore, Rutherford's atom is unstable.