Tag: physics

Questions Related to physics

In a car lift compressed air exert a force F1 on a small Piston having radius of 5 cm. This pressure is transmitted to second piston of radius 15 cm. If the mass of the car to be lifted is 1350 kg. What is F1?

archimedes' principle fluid pressure properties of matter physics

  1. $14.7\times 10^3 N$

  2. $1.47\times  10^2 N$

  3. $2.47\times  10^3 N$

  4. $24.7\times 10^2 N$

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Correct Option: C

A wooden block is taken to the bottom of a lake of water and then released . it rise up with a 

archimedes' principle fluid pressure properties of matter physics

  1. Constant acceleration

  2. Decreasing acceleration

  3. Constant velocity

  4. Decreasing velocity

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Correct Option: A

Pressure applied to an enclosed fluid is transmitted undiminished to every portion of the fluid and the walls of the containing vessel. This law was first formulated by

archimedes' principle fluid pressure properties of matter physics

  1. Bernoulli

  2. Archimedes

  3. Boyle

  4. Pascal

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Correct Option: A

A cube of wood supporting $200 \mathrm { gm }$ mass just floats in water in fully submerged state. When the mass is removed cube rises by $2 \mathrm { cm }$ above water level. Find the size of cube? (take $\rho _ { \text { water } } = 1000 \mathrm { kg } / \mathrm { m } ^ { 3 } )$

archimedes' principle fluid pressure properties of matter physics

  1. $10 \mathrm { cm }$

  2. $15 \mathrm { cm }$

  3. $20 \mathrm { cm }$

  4. $30 \mathrm { cm }$

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Correct Option: C

A piece of ice is floating in a beaker containing thick sugar solution of water. As the ice melts, the total level of the liquid:

archimedes' principle fluid pressure properties of matter physics

  1. increases

  2. decreases

  3. remains unchanged

  4. insufficient data

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Correct Option: A
Explanation:

Let $\rho $=density of sugar solution $> \rho _{w}$
m=mass of ice.
In floating condition weight=upthrust
$\therefore $   $mg=V _{I}\rho g$
or $\displaystyle V _{I}=\frac{m}{\rho }$          (i)
When ice melts, m mass of ice becomes m mass of water. Volume of this water formed.
$\displaystyle V _{F}=\frac{m}{\rho _{w}}$          (ii)
Since $\rho _{w}< \rho $, $V _{F}> V _{I}$. Hence level will increase.

A boat full of scrap iron is floating on water in a lake. If all the iron is dropped into the water, the level of water will:

archimedes' principle fluid pressure properties of matter physics

  1. go up

  2. fall down

  3. remain the same

  4. Can not be decided.

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Correct Option: B
Explanation:
According to Archimedes' principle, any body completely or partially submerged in a fluid at rest is acted upon by an upward, or buoyant force,the magnitude of which is equal to the weight of the fluid displaced by the body
As boat filled with scrap iron is floating on lake, buoyant force acting on boat is more than its weight.
                                              $F _b > W _b + W _{fe}$
since,                                    $W _b<W _b +W _{fe}$
therefore,level of water will fall down across the boat.

If a piece of wood just floats in water. What happens to it in ethanol?

archimedes' principle fluid pressure properties of matter physics

  1. It floats higher

  2. It stays as before

  3. It sinks

  4. First sinks and then rises

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Correct Option: C
Explanation:

At room temperature and standard pressure, the first family of alcohol (methanol, ETHANOL and iso-propyl) all have densities of about 0.79g/cc compare to water at the same conditions with a density of 1.0g/cc.

Since the density of ethanol is less than the density of water so, when a piece of wood which is just floating in water is placed in ethanol, sinks.

Which of the following instrument is used to measure the volume of a solid by water displacement ?

archimedes' principle fluid pressure properties of matter physics

  1. Thermometer

  2. Graduated cylinder

  3. Buret

  4. Salt bridge

  5. Conductivity tester

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Correct Option: B
Explanation:

Graduated cylinder  is used to measure the volume of a solid by water displacement. The volume of water displaced will be equal to the volume of the solid.

A boat is floating on the surface of water in a tank carrying steel balls. If the balls are thrown into the tank one by one, how will it affect the level of water?

archimedes' principle fluid pressure properties of matter physics

  1. It will rise

  2. It will fall

  3. It will remain unchanged

  4. First it will rise and then fall

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Correct Option: B

A dog is sitting in a boat which is floating in a pond. If the dog drinks some water from the pond then:

archimedes' principle fluid pressure properties of matter physics

  1. the level of water in the pond decreases

  2. the level of water in the pond increases

  3. the level of water in the pond first increases, then decreases

  4. the level of water in the pond remains unchanged

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Correct Option: D
Explanation:

There Will be no change in the water level of the pond, as the water which was drawn from the pond went to the man's body, thereby increasing his weight. So the decrease in level of water will be compensated by volume displaced by increase in weight of the man.

Therefore option $D$ is correct.