a. Volume of a cube = side \(\times\) side \(\times\) side
= 3 cm \(\times\) 3 cm \(\times\) 3 cm = 27 cubic cm or \(\mathrm{cm}^{3}\)
b. Volume of a cylinder \(=\pi \times(\text { radius })^{2} \times \text { height }\)
\(=22 / 7 \times 3 \times 3 \times 7=198 \mathrm{~m}^{3} .\)

(a) Area of rectangle = length \(\times\) breadth
= 12 \(\times\) 4 = 48 m²
(b) Area of circle
\(=\pi \times r^{2}=(22 / 7) \times 7 \times 7 \\ =154 \mathrm{~m}^{2}\)
(c) Area of triangle
\(=1 / 2 \times \text { base } \times \text { height } \\ =1 / 2 \times 6 \times 8=24 \mathrm{~m}^{2}\)

Area of a square = side \(\times \) side
= 1 m \(\times \) 1 m
= 1 m² or 1 square metre
Area of 10 squares = 1 square metre \(\times \) 10
= 10 square metre

There are two possible answers:
Velocity gives an idea of how fast the position changes. or Acceleration gives an idea of how fast the velocity changes.

Density (D) = mass (M) / volume (V).

Density = Mass / Volume
Hence, Volume = Mass / Density
\(=3000 / 8900=30 / 89 \\ =0.34 \mathrm{~m}^{3}\)

An object undergoes uniform acceleration when the change (increase or decrease) in its velocity for every unit of time is the same.

Physical quantities which can be obtained by multiplying, dividing or by mathematically combining the fundamental quantities are known as derived quantities.
Ex: Area, volume

True

False
Correct Statement: The region covered by the boundary of the plane figure is called its area.

Aluminium, Iron, Copper, Gold

metre/second²

Solid

c. Assertion is true but reason is false.

Stability:
Stability is a measure of the body's ability to maintain its original position.
The three types of stability are
(i) Stable equilibrium
(ii) Unstable equilibrium
(iii) Neutral equilibrium
Stable Equilibrium:
i) The frustum can be tilted through quite a big angle without toppling.
ii) Its centre of gravity is raised when it is displaced.
iii) The vertical line through its centre of gravity still falls within its base.
iv) So it can return to its original position.


Unstable Equilibrium:
i) The frustum will topple with the slightest tilting. Its centre of gravity is lowered when it is displaced.
ii) The vertical line through its centre of gravity falls outside its base.

Neutral Equilibrium:
(i) It causes frustum to topple.
(ii) The frustum will rolls about but does not topple.
(iii) Its centre of gravity remains at the same height when it is displaced.
(iv) The body will stay in any position to which it has been displaced.

i) Take a measuring cylinder and pour some water into it.
ii) Note down the volume of water from the readings of the measuring cylinder. Take it as V₁.
iii) Now take a small stone and tie it with a thread.
iv) Immerse the stone inside the water by holding the thread.
v) The stone should not touch the walls of the measuring cylinder.
vi) Note down the volume of water and take it to be V₂
vii) The volume of the stone is equal to the raise in the volume of water.
viii) Volume of stone = V₂ - V₁

Final velocity (v) = 20 m/s Initial Velocity (u) = 0 m/s.
Time (t) = 10 s
Acceleration (a) =?
\(\text { Acceleration } =\frac{\text { Change in velocity }}{\text { time }} \)
\(=\frac{\text { Final velocity }(\mathrm{v})-\text { Initial velocity }(\mathrm{u})}{\text { time }}=\frac{\mathrm{v}-\mathrm{u}}{\mathrm{t}}=\frac{20-0}{10} \)
Acceleration of the car = 2 m/s².

\(\mathrm{r} =1 \mathrm{~cm}=1 / 100 \mathrm{~m} \)
\(\mathrm{M} =33 \mathrm{~g}=33 / 1000 \mathrm{~kg} \)
\(\mathrm{D} =\mathrm{M} / \mathrm{V}\)
Volume of sphere \(\mathrm{V}=4 / 3 \pi \mathrm{r}^{3}\)
\(\mathrm{V} =4 / 3 \times 3.14 \times 1 / 100 \times 1 / 100 \times 1 / 100 \)
\(\mathrm{V} =4.186 / 1000000 \mathrm{~m}^{3} \)
\(\mathrm{D} =\mathrm{M} / \mathrm{V} \)
\(=33 \times 1000000 / 4.186 \times 1000 \)
\(=7880 \mathrm{~kg} / \mathrm{m}^{3} \)
Density of silver =7880 kg / m³

Given radius = 10 cm = 0.1m
π = 3.14
Area of a circular disc A = πr² (in m²)
Formula: Area of a circle A = πr²
= 3.14 \(\times\) 10 / 100  \(\times\) 10 / 100
= 0.0314m²
Solution: A = 0.0314m²

Clues - Across
1. KELVIN
2. VOLUME
3. DENSITY
4. CAPACITY
Clues-Down 
a. VELOCITY
b. CUBIC METRE
c. MERCURY
d. LIGHT YEAR