NEET (UG)

Practice Test 1 — Mechanical Properties of Solids & Fluids

12 questions • 18 minutes • auto-graded with full solutions

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Section A — MCQ (Single Correct)

Question 1

Stress has the same unit as:

Solution: Both stress and pressure are $\text{N/m}^2$.

Question 2

A wire of length $L$ extends by $\Delta L$ under a load. A wire of the same material and area but length $2L$ under the same load extends by:

Solution: $\Delta L \propto L$, so doubling length doubles extension.

Question 3

Which modulus exists for gases?

Solution: Gases resist only volume change (bulk modulus).

Question 4

The pressure at $5\ \text{m}$ depth in water ($\rho = 1000$, $g = 10$) due to the water column is:

Solution: $\rho g h = 1000\times10\times5 = 50000\ \text{Pa}$.

Question 5

An object floats with $\tfrac{3}{4}$ submerged in water. Its density is:

Solution: $\rho_{body} = 0.75\times1000 = 750\ \text{kg/m}^3$.

Question 6

An aeroplane wing generates lift because air moves:

Solution: Faster flow above ⇒ lower pressure above ⇒ upward lift (Bernoulli).

Question 7

The terminal velocity of a raindrop depends on its radius as:

Solution: Stokes' law: $v_t \propto r^2$.

Question 8

Excess pressure inside a liquid drop of radius $r$ is:

Solution: A drop has one surface: $\Delta P = 2T/r$.

Section B — Assertion & Reason

Question 9

A: Liquids cannot sustain a shear stress.
R: Liquids have no rigidity (shear) modulus and therefore flow.

Solution: Zero rigidity means any shear stress causes flow — R explains A.

Question 10

A: A small drop of liquid tends to be spherical.
R: Surface tension minimises the surface area for a given volume.

Solution: A sphere has the least surface area for a given volume, which surface tension favours — R explains A.

Question 11

A: Water rises higher in a narrower capillary tube.
R: Capillary rise is directly proportional to the tube radius.

Solution: A is true (rise is higher in narrower tubes), but R is false — capillary rise is inversely proportional to radius ($h \propto 1/r$).

Question 12

A: Pressure in a static liquid is the same at all points at the same depth.
R: Liquid pressure at a point depends only on depth, density and $g$, not on container shape.

Solution: Since $P = P_0 + \rho g h$ depends only on depth, equal depths give equal pressure — R explains A.