Question

help pls!!....from the chapter:FORCE & PRESSURE​

Answer 1

Given:

Weight of the brick = 40N

Length = 25cm

Breadth = 10cm

Height = 5cm

To find:

Pressure exerted by the brick when placed on all three sides one by one.

Solution:

We know that:

$\Longrightarrow \sf Pressure = \dfrac{Force \ exerted}{Area }$

Units:

Pressure ➝ n/m² or Pascal/Pa

Force exerted ➝ N

Area ➝ m²

(i) Base: 25cm × 10cm.

➝ Area = 25 × 10 cm²

➝ Area = 250 cm²

[Convert cm² → m² as Force is in Newton]

➝ Area = 250/10000 m²

➝ Area = 25/1000 m²

➝ Area = 0.025  m²

➝ Force = 40N

$\Longrightarrow \sf P = \dfrac{F}{A}$

$\Longrightarrow \sf P = \dfrac{40}{0.025}$

$\Longrightarrow \sf P = \dfrac{40}{0.025} \times \dfrac{1000}{1000}$

$\Longrightarrow \sf P = \dfrac{40000}{25}$

$\Longrightarrow \sf P = 1600 \ Pa$

Answer: 1600 Pa.

(ii) Base: 25cm × 5cm.

➝ Area = 25 × 5 cm²

➝ Area = 125 cm²

[Convert cm² → m² as Force is in Newton]

➝ Area = 125/10000 m²

➝ Area = 0.0125  m²

➝ Force = 40N

$\Longrightarrow \sf P = \dfrac{F}{A}$

$\Longrightarrow \sf P = \dfrac{40}{0.0125}$

$\Longrightarrow \sf P = \dfrac{40}{0.0125} \times \dfrac{10000}{10000}$

$\Longrightarrow \sf P = \dfrac{400000}{125}$

$\Longrightarrow \sf P = 3200 \ Pa$

Answer: 3200 Pa.

(ii) Base: 25cm × 5cm.

➝ Area = 10 × 5 cm²

➝ Area = 50 cm²

[Convert cm² → m² as Force is in Newton]

➝ Area = 50/10000 m²

➝ Area =  m²

➝ Force = 40N

$\Longrightarrow \sf P = \dfrac{F}{A}$

$\Longrightarrow \sf P = \dfrac{40}{0.005}$

$\Longrightarrow \sf P = \dfrac{40}{0.005} \times \dfrac{1000}{1000}$

$\Longrightarrow \sf P = \dfrac{40000}{5}$

$\Longrightarrow \sf P = 8000 \ Pa$

Answer: 8000 Pa.

Final solutions:

➝ Taking 25 × 10 cm as base, Pressure exerted is 1600 Pa.

➝ Taking 25 × 5 cm as base, Pressure exerted is 3200 Pa.

➝ Taking 10 × 5 cm as base, Pressure exerted is 8000 Pa.

Answer 2

Answer:

Given :

Weight of the brick = 40N

Length = 25cm

Breadth = 10cm

Height = 5cm

To find :

Pressure exerted by the brick when placed on all three sides one by one.

Solution :

We know that:

Pressure= Force/Area

Units:

Pressure → n/m² or Pascal/Pa

Force exerted → N

Area → m²

(i) Base: 25cm x 10cm.

Area 25 x 10 cm²

Area = 250 cm²

[Convert cm² → m² as Force is in Newton]

Area 250/10000 m²

→ Area =25/1000 m²

→ Area = 0.025 m²

Force = 40N

P = F/A

P =40/0.025

=40/0.025

=40000/25

P = 1600 Pa

Answer: 1600 Pa.

(ii) Base: 25cm x 5cm.

→ Area = 25 x 5 cm²

Area = 125 cm²

[Convert cm² → m² as Force is in Newton]

Area 125/10000 m²

Area 0.0125 m²

Force = 40N

P =F/ A

P=40/0.0125

P=400000/125

P = 3200 Pa

Answer: 3200 Pa.

(iii) Base: 10cm x 5cm.

→ Area = 10 x 5 cm²

Area = 50 cm²

[Convert cm² → m² as Force is in Newton]

Area 50/10000 m²

→ Area = m²

Force = 40N

P=F/A

P=40 /0.005

P=40000/5

P = 8000 Pa

Answer: 8000 Pa.

Final solutions:

→ Taking 25 x 10 cm as base, Pressure exerted is 1600 Pa.

→ Taking 25 x 5 cm as base, Pressure exerted is 3200 Pa.

→ Taking 10 x 5 cm as base, Pressure exerted is 8000 Pa.