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The initial velocity of a particle is $u$ (at $t = 0$) and the acceleration $f$ is given by $at$. Which of the following relations is valid?
Preeti reached the metro station and found that the escalator was not working. She walked up the stationary escalator in time t₁. On other days, if she remains stationary on the moving escalator, then the escalator takes her up in time t₂. The time taken by her to walk upon the moving escalator will be:
The acceleration of a moving body can be found from:
A person standing on the floor of an elevator drops a coin. The coin reaches the floor in time $t_1$ if the elevator is moving uniformly and time $t_2$ if the elevator is stationary. Then:
The graph between the displacement $x$ and time $t$ for a particle moving in a straight line is shown in the figure. During the intervals OA, AB, BC, and CD, the acceleration of the particle is:
A wave in a string has an amplitude of $2 \text{ cm}$. The wave travels in the positive direction of the x-axis with a speed of $128 \text{ m/s}$ and it is noted that $5$ complete waves fit in the $4 \text{ m}$ length of the string. The equation describing the wave is:
A siren emitting a sound of frequency $800\text{ Hz}$ moves away from an observer towards a cliff at a speed of $15\text{ ms}^{-1}$. The frequency of sound that the observer hears in the echo reflected from the cliff will be: (Take, velocity of sound in air = $330\text{ ms}^{-1}$)
A tuning fork with a frequency of $800 \text{ Hz}$ produces resonance in a resonance column tube with the upper end open and the lower end closed by the water surface. Successive resonances are observed at lengths of $9.75 \text{ cm}$, $31.25 \text{ cm}$, and $52.75 \text{ cm}$. The speed of the sound in the air is:
Given below are two statements: Assertion (A): A glass tube partially filled with water represents an open organ pipe. Reason (R): The open end corresponds to an antinode and the end in contact with water, to a node. In the light of the above statements, choose the correct answer from the options given below:
The $4^{\text{th}}$ overtone of a closed organ pipe is the same as that of the $3^{\text{rd}}$ overtone of an open pipe. The ratio of the length of the closed pipe to the length of the open pipe is:
The length of the string of a musical instrument is $90\text{ cm}$ and has a fundamental frequency of $120\text{ Hz}$. Where should it be pressed to produce a fundamental frequency of $180\text{ Hz}$?
The peak voltage of the ac source is equal to
A biconvex lens has radii of curvature, $20\text{ cm}$ each. If the refractive index of the material of the lens is $1.5$, the power of the lens is
At a point A on the earth's surface the angle of dip, $\delta = +25^{\circ}$. At a point B on the earth's surface the angle of dip, $\delta = -25^{\circ}$. We can interpret that:
In total internal reflection when the angle of incidence is equal to the critical angle for the pair of media in contact, what will be angle of refraction?
A hollow metal sphere of radius R is uniformly charged. The electric field due to the sphere at a distance r from the centre
For transistor action, which of the following statements is correct?
A wire of length L, area of cross section A is hanging from a fixed support. The length of the wire changes to $L_1$ when mass M is suspended from its free end. The expression for Young's modulus is :
If force [F], acceleration [A] and time [T] are chosen as the fundamental physical quantities. Find the dimensions of energy.
Six similar bulbs are connected as shown in the figure with a DC source of emf E and zero internal resistance. The ratio of power consumption by the bulbs when (i) all are glowing and (ii) in the situation when two from section A and one from section B are glowing, will be :