A boat loaded with rocks floats in the middle of a swimming pool. A man in the boat throws the rocks overboard. The level of water in the pool will
increase
decrease
remain the same
first decrease and then increase
Correct Answer :
B. decrease
Related Questions
We cannot see and without the aid of a telescope
Neptune and Pluto
Jupiter and Saturn
Venus and Mars
Venus and Saturn
A heavenly body similar in nature to the sun intensely hot glowing mass that produces its energy by thermonuclear reactions is
a planet
a meteor
a star
a comet
Which of the following can produce electricity?
resistor
thermocouple
light bulb
neon tube
In a concert hall reverberation is controlled by
reduction of seating capacity in the hall
increase of sound intensity in the hall
lining the walls, with leather panels put on over a layer of sound absorbent glass fibre
by opening the doors and windows of concert hall
A hydrogen bomb is based on
nuclear fusion
nuclear fission
Both (a) and (b) above
Neither (a) nor (b)
We always see only one side of the moon because
the sun comes in between the earth and moon
the moon is stationary
the time taken by the moon to rotate on its axis is the same as the time taken by it to revolve round the earth
moon revolves round the sun
The completely dark portion of a shadow of an object is known as
umbra
penumbra
image
black portion of light
The image formed by a plane mirror is
of the same size as the object
at the same distance behind the mirror as the object is in front of it
virtual and laterally inverted
All the above
During thunder storm you are travelling in a car. To protect yourself from the lightning you will have to
remain in the car
get out of the car and lie flat in the ground
abandon the car and take shelter under a nearby tree
touch the nearest electric pole
If a man wants to hear clearly the echo of a sound produced by him from a hill, the hill should be away from him by a minimum distance of
330 m
33 m
16.5 m
165 m
Atoms which have the same atomic number but different mass numbers are called
isobars
isomers
isotones
isotopes
In an oil lamp, holes are provided below the chimney so that
necessary oxygen for burning of oil may be provided
the convection current of air may be maintained to keep the lamp burning
the brightness of the lamp may be increased
All the above
A workman was working on a rail track. A young boy at a distance holds his ear close to the railway track. The boy was able to hear the sound of each blow or the workman twice. It is because
speed of sound is greater in steel than in air
speed of sound is greater in air than in steel
part of sound waves is reflected between rail tracks
the boy's ears are at a different distance from the source
Pieces of camphor placed on water move about rapidly. This is because of
diffusion
viscosity
surface tension
capillarity
The aneroid barometer uses
mercury
distilled water
alcohol
does not use any liquid
A rod of brass is held in hand and rubbed with fur. The rod is found to have
no charge
positive charge
negative charge
can't be said
In compact porous soil, the rising of the water is due to
capillarity
cohesion
adhesion
viscosity
The end product in the uranium disintegration series is
lead
zinc
carbon
tin
The phenomenon of spontaneous disintegration of certain heavy nuclei is termed
radioactivity
fission
fusion
implosion
Sound travels fastest in
air
water
iron
vacuum
When a bowler spins a ball, it changes its direction in the air. This is due to
turbulence caused by the wind
buoyancy of air
unequal pressures acting on it
sudden change in the direction of the wind
Which of the following can produce electricity?
resistor
thermocouple
light bulb
neon tube
The minimum velocity required by a satellite to escape earth's gravitational pull is
18 km/s
11.2 km /s
21 km/s
35 km/s
The property of a fluid by which it resists relative motion within itself is known as
cohesive force
surface tension
diffusion
viscosity
The function of a ruse wire is
to stabilise the voltage
to decrease the current supply
to increase the current supply
to prevent an unduly high current from passing through a circuit
Mercury does not stick to glass because
cohesive forces between the mercury molecules are greater than adhesive forces between mercury and glass molecules
the adhesive forces between mercury and glass molecules are greater than the cohesive forces
both the cohesive and adhesive forces are equal
None of the above
Lightning is produced when
similar charges of electricity rush towards each other and then get repelled
clouds strike against impurities in air and the friction burns up these impurities
strong opposite charges in different clouds break down the resistance offered by the intervening air
water vapour produces electricity in the clouds
The instrument used to measure the strength of electric current at a point is
Ammeter
Altimeter
Adrinometer
Anemometer
A stone floor feels cold to the bare feet but a carpet on the same floor feels warm. This is because
the floor and carpet are at different temperatures
the stone conveys the heat away from the feet more rapidly than the carpet
the carpet is a better conductor of heat than the stone
the human body maintains a constant temperature
A sensitive instrument susceptible to magnetic infiuence can be protected from external magnetic field by
enclosing it in a thick walled iron box
wrapping it with an insulator
by placing it inside a glass case
by surrounding it with fine copper gauze