VITEEE 2019 :: Physics :: General questions

• Physics - General questions

If the differential equation for a simple harmonic motion is $\frac{d^{2}y}{dt^{2}}+2y = 0$, the time period of the motion is

Answer:

Explanation:

The differential equation of simple harmonic motion is

$\frac{d^{2}y}{dt^{2}}+2y = 0$ or $\frac{d^{2}y}{dt^{2}} = -2y$ ...(i)

Standard equation of simple harmonic motion is

$\frac{d^{2}y}{dt^{2}}$ =- ω² y   ....(ii)

Comparing eq. (i) and (ii)

ω² = 2 or ω = √2

As we know, 

$\omega = \frac{2\pi}{T}$

.'. TimePeriod, T = $\frac{2\pi}{\omega}$ 

= $\frac{2\pi}{\sqrt{2}}$ = $\pi\sqrt{2}$ sec

When a system is taken from state i to state f along the path iaf, it is found that Q = 50 cal and W = 20 cal. Along the path ibf Q = 36 cal W along the Path ibf is

Answer:

Explanation:

For path iaf, Q = 50 cal W = 20 cal

By the first law of thermodynamics,

ΔU = Q - W = 50 - 20 = 30 cal.

For path ibf

Q' = 36 cal

W' =?

Or, W' = Q' - ΔU'

Since the change in internal energy does not depend on the path,

therefore ΔU' = 30cal

.'. W' = Q' - ΔU' = 36 - 30 = 6 cal.

The surface of a metal is illuminated with a light of 400 nm. The kinetic energy of the ejected Photoelectrons was found to be 1.68  eV. The work function of the metal is?

(hc =  1240eV.nm)

Answer:

Explanation:

Energy of incident light, E = $\frac{12400}{\lambda (Å)}$

E = $\frac{1240}{400}$ = 3.1 eV

E =  W₀ + K_max

 3.1 = W₀+ 1.68 = W₀= 1.42 eV

A planet revolves in an elliptical orbit around the sun. The semi-major and semi-minor axes are a and b. Then the square of time period T is directly proportional to

Answer:

Explanation:

The square of the period of the planet is directly proportional to the cube of the semi-major axis of the elliptical orbit.

T² $\propto$ a³

A liquid is allowed to flow into a tube of truncated cone shape. Identify the correct statement from the following.

Answer:

Explanation:

The theorem of continuity is valid.

.'. A₁v₁ρ = A₂v₂ρ 

As the density of the liquid can be taken as uniform.

.'. A₁v₁ = A₂v₂

Smaller the area, greater the velocity

• Physics - General questions