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A person standing in front of a cliff fires a gun and hears its echo after 3 s. If the speed of sound in air is 336 ms−1.
- Calculate the distance of the person from the cliff.
- After moving a certain distance from the cliff, he fires the gun again, and this time the echo is heard 1.5 s later than the first. Calculate the distance that the person moved.
Concept: Moment (Turning Effect) of a Force or Torque
The kinetic energy of a given body depends on the ______.
Concept: Mechanical Energy > Kinetic Energy (K)
For the following scenario, state whether the work done by gravity is positive, negative, or zero.
A person walks on a levelled road.
Concept: Work Done by the Force of Gravity (W = mgh)
For the following scenario, state whether the work done by gravity is positive, negative, or zero.
A person climbs a ladder.
Concept: Work Done by the Force of Gravity (W = mgh)
For the following scenario, state whether the work done by gravity is positive, negative, or zero.
A car in neutral gear is coming down the slope.
Concept: Work Done by the Force of Gravity (W = mgh)
A block and tackle system of pulleys has a velocity ratio of 4.
- Draw a labelled diagram of the system indicating clearly the direction of the load and effort.
- Calculate the potential energy of the load 100 kgf lifted by this pulley to a height 5 m. (g = 10 ms−2)
Concept: Pulley
Concept: Refraction of Light Through a Rectangular Glass Block
Name the principle on the basis of which optical fibres work.
Concept: Total Internal Reflection
The diagram below shows a fish in the tank and its image seen on the surface of the water.

Name the phenomenon responsible for the formation of this image.
Concept: Total Internal Reflection
Why does sun appear red at sunrise and sunset?
Concept: Applications of Scattering of Light
Calculate the shortest wavelength of electromagnetic radiation present in Balmer series of hydrogen spectrum.
Concept: Electromagnetic Spectrum
Name the waves used for echo depth sounding.
Concept: Echo >> Use of Echoes
Two sound waves X and Y have the same amplitude and the same wave pattern but their frequencies are 60 Hz and 120 Hz respectively, then ______.
Concept: Sound Waves

The above picture shows a mother pushing her daughter sitting on a swing. The swing is going through the positions A, B, C where A and C are extreme positions and B is the mean position.
- Which is the right position i.e. at A, B or C, for the mother to give a constant periodic push to the swing every time in the forward direction to increase the amplitude of the swing? (1)
- Name the phenomenon involved in this. (1)
- Explain with this example how this phenomenon helps to increase the amplitude of the swing. (2)
Concept: Resonance (a special case of forced vibrations) >> Examples of Resonance
Which particles are responsible for current in conductors?
Concept: Electrical Power
Concept: Resistance of a System of Resistors >> Resistors in Series
The diagram below shows a cardboard on which iron filings are kept. A wire bent in the form of a loop is seen passing through the cardboard. When current flows through it, the iron filings arrange themselves as shown below.

- State the polarities of the battery at A and B.
- State the effect on the magnetic field if an iron rod is held along the axis of the coil.
- State one way to:
- Change the polarity of the coil.
- Decrease the strength of the magnetic field around the coil.
Concept: Terminal Voltage of a Cell
The circuit depicted in the figure is employed for studying Ohm’s Law. Instead of using a standard resistor, a student opts for a glass tube filled with mercury (tube 1), connected to the circuit through two electrodes, E1 and E2. He records the readings of the ammeter and voltmeter, thereby calculating the resistance. The student repeats the experiment by substituting tube 1 with tube 2, where the same amount of mercury fills tube 2.

Neglecting internal resistance of the cell use (> or < or =) to compare:
- the resistance in both the cases.
- the voltmeter readings in both the cases.
- the specific resistance in both the cases.
Concept: Ohm's Law
To which wire of a cable in a power circuit should the metal case of geyser be connected.
Concept: Earthing
To which wire should the fuse be connected?
Concept: Fuse
