VITEEE 2018 :: Physics :: General questions

• Physics - General questions

The temperature of equal masses of three different liquids A, B and C are 12ºC, 19ºC and 28ºC respectively. The temperature when A and B are mixed is 16ºC and when B and C are mixed is 23ºC. The temperature when A and C are mixed is

Answer:

Explanation:

Heat gain = Heat lost

C_A (16 - 12) = C_B(19 - 16) → $\frac{C_{A}}{C_{B}} = \frac{3}{4}$

and C_B (23 - 19) = C_C(28 - 23)  → $\frac{C_{B}}{C_{C}} = \frac{5}{4}$

 → $\frac{C_{A}}{C_{C}} = \frac{15}{16}$         .....(i)

If θ is the temperature when A and C are mixed then,

C_A (θ - 12) = C_C(28 - θ) → $\frac{C_{A}}{C_{C}} = \frac{28 - θ}{θ - 12}$ ....(ii)

On solving equations (i) and (ii) θ  = 20.2ºC

A square loop, carrying a steady current I. is placed in a horizontal plane near a long straight conductor carrying a steady current I₁ at a distance d from the conductor as shown in the figure. The loop will experience

Answer:

Explanation:

F₁ > F₂ as $F \propto\frac{1}{d}$, and F₃ and F₄ are equal and opposite. Hence, the net attraction force will be towards the conductor.

The length of elastic string, obeying Hooke's law is l₁ metres when the tension 4N and l₂ metres when the tension is 5N. The length in metres when the tension is 9N is 

Answer:

Explanation:

Let l₀ be the unstretched length and l₃ be the length under a tension of 9N. Then

Y = $\frac{4l_{0}}{A(l_{1}-l_{0})}$ = $\frac{5l_{0}}{A(l_{2}-l_{0})}$

= $\frac{9l_{0}}{A(l_{3}-l_{0})}$ 

These give

$\frac{4}{(l_{1}-l_{0})}$ = $\frac{5}{(l_{2}-l_{0})}$ 

l₀ = 5l₁ - 4l₂

Further, $\frac{4}{(l_{1}-l_{0})}$ = $\frac{9}{(l_{2}-l_{0})}$

Substituting the value of l₀ and solving, and we get l₃ = 5l₂ - 4l₁

The current sensitivity of a moving coil galvanometer depends on

Answer:

Explanation:

Current sensitivity = $\frac{nBA}{K}$

where K is constant of torsional rigidity.

The principle of conservation of linear momentum can be strictly applied during a collision between two particles provided the time of impact.

Answer:

Explanation:

In physics, collision does not means that one particle strikes another particle. In fact, two particles may not even touch each other & may still say to be colliding. The necessary requirements of collision are

• A large force for a relatively short time (i.e., an impulse) acts on each colliding particle.
• The motion of the particles (at least one of the particle) is changed abruptly.
• The total momentum (as also the total energy) of particles remains conserved.

• Physics - General questions