Question

Fill in the blanks :
(a) The volume of a cube of side 1cm is equal to _____$m^{3}$
(b) The surface area of a solid cylinder of radius 2.0 cm and height 10.0 cm is equal to _____ $(mm)^{2}$
(c) A vehicle moving with a speed of 18 km $h^{-1}$ cover_____ m in 1s.
(d) The relative density of lead is 11.3. Its density is____ g $cm^{-3}$ or _____ kg $m^{-3}$.

Answer 1

Hello!!

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Answers :

a) 10 to the power of -6 m3

b)Radius, r = 2.0 cm = 20 mm (convert cm to mm)

Height, h = 10.0 cm =100 mm

The formula of total surface area of a cylinder S = 2πr (r + h)

Putting the values in this formula, we get

Surface area of a cylinder S = 2πr (r + h = 2 x 3.14 x 20 (20+100)

= 15072 = 1.5 × 104 mm2

The surface area of a solid cylinder of radius 2.0 cm and height 10.0 cm is equal to 1.5 × 104 mm2

c)Using the conversion,

Given,

Time, t = 1 sec

speed = 18 km h-1 = 18 km / hour

1 km = 1000 m and 1hour = 3600 sec

Speed = 18 × 1000 /3600 sec = 5 m /sec

Use formula

Speed = distance / time

Cross multiply it, we get

Distance = Speed × Time = 5 × 1 = 5 m

A vehicle moving with a speed of 18 km h–1covers 5 m in 1 s.

(d) Density of lead = Relative density of lead × Density of water

Density of water = 1 g/cm3

Putting the values, we get

Density of lead = 11.3 × 1 g/ cm3

= 11.3 g cm-3

1 cm = (1/100 m) =10–2 m3

1 g = 1/1000 kg = 10-3 kg

Density of lead = 11.3 g cm-3 = 11.3

Putting the value of 1 cm and 1 gram

11.3 g/cm3 = 11.3 × 10-3 kg (10-2m)-3 = 11.3 ×10–3 × 106 kg m-3 =1.13 × 103 kg m–3

The relative density of lead is 11.3. Its density is 11.3 g cm-3 g cm–3 or 1.13 × 103 kg m–3.

Thanks :)