Assertion: Use of ball bearings between two moving parts of a machine is a common practice.
Reason: Ball bearings reduce vibrations and provide good stability.
If both assertion and reason are true and reason is the correct explanation of the assertion
If both assertion and reason are true but reason is not the correct explanation of the assertion
If assertion is true, but reason is false
Both assertion and reason are false statements
Assertion: A thin stainless steel needle can lay floating on a still water surface.
Reason: Any object floats when the buoyancy force balances the weight of the object.
If both assertion and reason are true and reason is the correct explanation of the assertion
If both assertion and reason are true but reason is not the correct explanation of the assertion
If assertion is true, but reason is false
Both assertion and reason are false statements
A candle of diameter d is floating on a liquid in a cylindrical container of diameter D ( D >> d ) as shown in figure. If it is burning at the rate of 2 cm/hour then the top of the candle will
remain at the same height
fall at the rate of 1 cm/hour
fall at the rate of 2 cm/hour
go up at the rate of 1 cm/hour
B.
fall at the rate of 1 cm/hour
Archimedes' principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces and acts in the upward direction at the centre of mass of the displaced fluid.
When an object is placed in a fluid, the fluid exerts an upward force we call buoyant force.
Just for the concept of Archimedes' principle
In the above figure, pressure due to the weight of a fluid increase with depth since P = hρg. This pressure and associated upward force on the bottom of the cylinder are greater than the downward force on the top of the cylinder. The difference is the buoyant force FB ( Horizontal Forces Cancel )
Initial weight of the candle = weight of the liquid displaced
ρcVc g = ρL ( volume displaced ) g
⇒ ρc 2 Lg = ρL Lg
⇒ ....(i)
when 2 cm has been burnt, total length = 2L 2
But ρc (2L 2 ) = ρL ( L x )
ρc 2 ( L 1 ) = 2ρc ( L x ) [ using eqn. (i) ]
∴ x = 1 cm
Outside also it has decreased to 1 cm as the total decrease is 2 cm. The level of the candle comes down at half the rate burning.
A given shaped glass tube having uniform cross section is filled with water and is mounted on a rotatable shaft as shown in figure. If the tube is rotated with a constant angular velocity ω when
water levels in both sections A and B go up
water level in section A goes up and that in B comes down
water level in section A comes down and that in B it goes up
water levels remain same in both sections
Assertion: Specific gravity of a fluid is a dimensionless quantity
Reason: : It is the ratio of density of fluid to the density of water.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
Assertion: For Reynold number Re > 2000, the flow of fluid is turbulent.
Reason: Inertial forces are dominant compared to the
viscous forces at such high Reynold numbers.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
A sphere of mass Mand radius R is falling in a viscous fluid. The terminal velocity attained by the falling object will be proportional to
R2
R
1/R
1/R2
The old age arteries carrying blood in the human body become barrow resulting in an increase in blood pressure. This follows from
Pascal's law
Stoke's law
Bernoulli's principle
Archimedes principle
Assertion: Smaller drops of liquid resist deforming forces better than the larger drops.
Reason: Excess pressure inside a drop is directly proportional to its surface area
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If assertion is true but reason is false
Bernoulli's equation is a consequence of conservation of
energy
linear momentum
angular momentum
mass