Question

Please answer these questions don't give improper answer 1. On what factor/ factors pressure depends? 2. Show that 1Pa=10dyn/cm2. 3. A blunt knife or a sharp knife which one you want to use to cut an apple. Why? 4. Why luggage bag's straps are wider?

Answer 1

Factors to Explain -

1. On what factor/ factors pressure depends ?

2. Show that 1 Pa = 10 dyn / cm² .

3. A blunt knife or a sharp knife which one you want to use to cut an apple. Why?

4. Why luggage bag's straps are wider?

Solution -

1.

We know that -

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

So , pressure is directly proportional to force and is indirectly proportional to the cross sectional area.

Hence , we can state that pressure depends on the two following factors -

1¹ . It depends on the force applied on the body .

1² . It depends on the cross sectional area .

2.

We know that -

1 dyne is equal to $\sf{ 10^ ( -5 ) }$ Newton's .

1 cm = 0.01 m

=> 1 cm^2 = ( 1 × 10^( -4 )) m ^ 2

=> 1 Pascal

=> 10 × [ 10^ ( -5 ) ] N / [ 10 ^ ( -4 ) ] m²

=> 1 N / m²

Hence Shown ...

3.

The tip of a blunt knife has a larger cross sectional area than that of a sharp knife .

We know that -

Pressure is inversely proportional to cross sectional area .

So, as the cross sectional area increases , the pressure decreases .

Thus , for a same amount of pressure , it is harder to cut an apple with a blunt knife .

4.

Wider luggage bag straps , increase the cross sectional area.

This in turn reduces the pressure on the hands of the carrier , enabling him to carry more load easily .

__________

Answer 2

1. On what factor/ factors pressure depends?

A→ Pressure depends upon two factors, namely :-

• Force applied
• Area on which the force is applied

The relation formed between pressure, force and area is :-

Pressure = Force ÷ Area

⇒P = F/A

We conclude :-

P ∝ F & P ∝ 1/A

If force increases, pressure increases. If area increases, pressure decreases, or vice-versa.

$\rule{180}2$

2. Show that 1 Pa = 10 dyn/cm².

A→ Dyne per square CGS unit of pressure. Pascal is a metric unit of pressure.

We know,

1 dyne equals 1 gram accelerated by 1 centimeter per second per second.

→ 1 Dyne per Square Centimetre equals 0.1 pascals.

⇒0.1 Pa = 1 dyn/cm²

⇒0.1 × 10 Pa = 1 × 10 dyn/cm²

$\bigstar$⇒1 Pa = 10 dyn/cm²

$\rule{180}2$

3. A blunt knife or a sharp knife which one you want to use to cut an apple. Why?

A→ I would choose a sharp knife to cut an apple, because the surface area of a sharp knife is comparatively less to a blunt knife. So, we know, if the area decreases, then the pressure applied increases (P ∝ 1/A). Increased pressure allows me to cut the apple easily.

$\rule{180}2$

4. Why luggage bag's straps are wider?

A→ If the area increases, the pressure decreases simultaneously. Luggage bags usually have broad straps so that the weight of the bag may fall over a large area on the shoulder producing less pressure on the shoulder. And the less the pressure is, it will be easier for the person to carry the luggage easily, flawlessly and comfortably.