VITEEE 2017 :: Physics :: General questions

• Physics - General questions

In which sequence the radioactive radiations are emitted in the following nuclear reaction?

$_{z}X^{A}\rightarrow _{z+1}Y^{A} \rightarrow_{z-1}K^{A-4}\rightarrow_{z-1}K^{A-4}$

Answer:

Explanation:

$_{z}X^{A}\underrightarrow  {-\beta^{0}}_{z+1}Y^{A}$

             $ \underrightarrow{_{2}He^{4}}_{z-1}K^{A-4}$

                                $\underrightarrow{_{0}\gamma^{0}}{z-1}K^{A-4}$

Two bodies A and B having masses in the ratio of 3 : 1 possess the same kinetic energy. The ratio of linear momentum of B to A is

Answer:

Explanation:

As $\frac{1}{2}m_Av_A^2 = \frac{1}{2}m_{B}v_B^2$

$\frac{v_{A}}{v_{B}} = \sqrt{\frac{m_{B}}{m_{A}}}$

$\frac{P_{B}}{P_{A}} = \frac{m_{B}v_{B}}{m_{A}v_{A}}$

$\frac{m_{B}}{m_{A}}\sqrt{\frac{m_{A}}{m_{B}}}  =\sqrt{\frac{m_{B}}{m_{A}}}$ = $\frac{1}{\sqrt{3}}$

If the kinetic energy of a moving particle is E, then the de-Broglie wavelength is

Answer:

Explanation:

E = $\frac{1}{2}mv^{2}$ or $mv = \sqrt{2mE}$

So $\lambda = \frac{h}{mv}$ = $\frac{h}{\sqrt{2mE}}$

A 5000 kg rocket is set for vertical firing. The exhaust speed is 800 m/s. To give an initial upward acceleration of 20 m/s², the amount of gas ejected per second to supply the needed thrust will be (Take g = 10 m/s²)

Answer:

Explanation:

Given :

Mass of rocket (m) = 5000 Kg

Exhaust speed (v) = 800 m/s

Acceleration of rocket (a) = 20 m/s²

Gravitational acceleration (g) = 10 m/s²

We know that upward force

F = m (g + a) = 5000 (10 +20) = 5000 x 30 = 150000N.

We also know that amount of gas ejected

$\frac{dm}{dt}=\frac{F}{V}=\frac{150000}{800}$=187.5kg/s

• Physics - General questions