Question

Read each of the situation described below. For each:
 state whether it is describe to have high pressure or low pressure
 explain why this is desirable.
Use the words force, area, and pressure in your answers.
1. A hotel has a lounge with a wooden dance floor. A notice says that people must not wear stiletto heels.[2]
2. A butcher regularly sharpens the knives which he uses to cut up meat.[2]
3. A needle used for sewing has a sharp point at one end. The person sewing often wears a thimble on a finger to push the needle through the fabric.[2]
Calculations involving pressure
2
1. An elephant weighs 60 000 N. It stands on four feet. Each foot has an area of 0.1 m .
a. Calculate the total area of the elephant’s feet. [1] .............................................................................................................................
b. Calculate the pressure the elephant exerts on the ground. [2] .............................................................................................................................
c. The elephant lifts one foot off the ground. Calculate the pressure it now exerts on the ground. [2]
.............................................................................................................................
2
2. A force of 6 N acts on an area of 2 m . What force acts on each square metre?
What is the pressure on the surface? [3] ................................................................................................................................... ...................................................................................................................................

Answer 1

Answer:

2 a)

Total area of contact of elephant foot is

A = 0.4 square meter

2 b)

Pressure due to elephant weight is given as

$P = 1.5 \times 10^5 Pa$

2 c)

When elephant lift its one foot then total pressure is

$P = 2\times 10^5 Pa$

3)

Pressure on the surface and force on unit area is

$P = 3 Pa$

Explanation:

As we know that pressure is ratio of force and area perpendicular to the applied force

So we have

1. A hotel has a lounge with a wooden dance floor. A notice says that people must not wear stiletto heels.

Here less pressure is required on the floor so the surface area must be large

2. A butcher regularly sharpens the knives which he uses to cut up meat.

Here large pressure is required so the area of contact must be small

3. A needle used for sewing has a sharp point at one end. The person sewing often wears a thimble on a finger to push the needle through the fabric.

Here large pressure is required so the area of contact must be small

2 a)

Since elephant has four foot

so we have total contact area given as

A = 4(0.1) = 0.4 square meter

2 b)

Pressure due to elephant weight is given as

$P = \frac{F}{A}$

$P = \frac{60000}{0.4}$

$P = 1.5 \times 10^5 Pa$

2 c)

When elephant lift its one foot

Now we have

$P = \frac{60000}{0.3}$

$P = 2\times 10^5 Pa$

3)

When applied force is given as

F = 6 N

Area of contact is 2 square meter

Now the pressure is given as

$P = \frac{6}{2}$

$P = 3 Pa$

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Topic : pressure

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Answer 2

Answer:

Please don't warn me or delete the my answers.