Thrust and Pressure

Q.

How is pressure related to force and area

Q.

What is the relationship between pressure and the area of contact?

Q.

A man applies a force of $20N$ on an area of ${2cm}^2$. Calculate the pressure on that area.

1. Pa

2. Pa

3. Pa

4. Pa

Q.

When a porter uses a round piece of cloth on his head while carrying luggage, it reduces pressure by increasing the area of contact.

1. True

2. False

Q. A floor has a mximum loading capacity of 5 kN $m^{-2}$. Which of the following is allowed on this floor? (Take g = 10 $Nk{g}^{-1}$)

1. A designers table weighing 1000 N stands on 3 legs, each leg has a contact area of 0.1 $c{m}^2$ with the floor.
2. A 50 kg lady wears a pair of high heel shoes, each shoe has a contact area of 9 $c{m}^2$ with the floor.
3. An elephant weighing 50 kN stands on 4 legs with each foot covering 400 $c{m}^2$ of the floor.
4. A 100 kg washing machine stands on a surface area of 6500 $c{m}^2$.

Q.

Give reason : “The base of tall buildings are made wider”.

Q.

Explain the following :

a. Why can't we hammer a nail by its head on the wood?

b. A sharp knife cuts better than a blunt knife. Why? [3 MARKS]

Q.

Why the base of high buildings is made wider?

Q. There are two school bags A & B. The bag A is provided with a broader strap than the bag B. For the same load, a student likes the bag A as he feels more comfortable with it. This must be because:

1. The straps of the bag A produce less pressure.
2. The straps of the bag B produce less pressure.
3. The straps of the bag B produce more pressure.
4. The force experienced from the bag A is lesser than that from B.

Q.

A person exerts the pressure of $48\mathrm{Pa}$ by applying a force of$24\mathrm{N}$on a box. Calculate the area over which the force is applied.

Q.

A turban on the head of a porter reduces the pressure by increasing the area of contact.

1. True
2. False

Q.

A body of dimensions $2m\times 3m\times 4m$ is acted upon by a force of $50N$ on the top surface $(2m\times 3m)$. The pressure due to the force on that surface is

1. $\frac{25}{6}Pa$.

2. $\frac{25}{3}Pa$.

3. $\frac{25}{12}Pa$.

4. $\frac{50}{3}Pa$.

Q.

The magnitude of force in a spring depends on

1. Spring cannot exert force

2. Spring constant 'K'

3. Length of elongation or length of compression 'x'

4. None of the above

Q.

Porters place a piece of cloth on their head to reduce the pressure.

1. True

2. False

Q.

Is pressure scalar or vector?

Q.

What name is given to the force acting on a unit area of an object?

Q.

When can we say that the pressure is getting equally divided?

Q. A thrust of $20N$ is acting on an area of $2m^2$. How much pressure is acting on the surface?

1. $\text{5 N}{m}^{-2}$

2. $\text{10 N}{m}^{-2}$

3. $\text{20 N}{m}^{-2}$

4. $\text{40 N}{m}^{-2}$

Q.

A body of dimensions $2m\times 3m\times 4m$ is acted upon by a force of 50N on the top surface $(2m\times 3m)$. The pressure due to the force on that surface is

1. $\frac{50}{8}Pa$

2. $\frac{50}{3}Pa$

3. $\frac{50}{6}Pa$

4. $\frac{10}{6}Pa$

Q.

A body of dimensions $2m\times 3m\times 4m$ is acted upon by a force of $50N$ on the top surface $(2m\times 3m)$. The pressure due to the force on that surface is

1. $\frac{250}{6}Pa$.

2. $\frac{50}{7}Pa$.

3. $\frac{60}{7}Pa$.

4. $\frac{50}{6}Pa$.

Q.

Thrust and pressure are dimensionally similar.

1. True
2. False

Q. A thrust of $20N$ is acting on an area of $2m^2$. How much pressure is acting on the surface?

1. $40N{m}^{-2}$
2. $5N{m}^{-2}$
3. $10N{m}^{-2}$
4. $20N{m}^{-2}$

Q.

Statement 1: For the same force acting on two different surfaces, more pressure is developed on the surface with a smaller area.
Statement 2: Pressure is defined as force per unit area.

1. Both the statements are true and statement 2 is the correct explanation of statement 1.

2. Statement 1 is false and statement 2 is true.

3. Statement 1 is true and statement 2 is false.

4. Both the statements are true and statement 2 is not the correct explanation of statement 1.

Q. A sharp knife cuts better than a blunt knife. Which of the following options gives the correct reason for this?

1. A sharp knife is heavier than a blunt knife.
2. Sharp knives are usually made of silver which has more strength.
3. A sharp knife has a smaller contact surface and hence applies more pressure.
4. A sharp knife has more surface area and hence applies more pressure.

Q.

Statement 1: For the same load or force acting through two different surfaces, more pressure is developed on the surface with a smaller area.
Statement 2: Pressure is defined as force per unit area.

1. Statement 1 is true, Statement 2 is true and Statement 2 is the correct explanation of Statement 1.

2. Statement 1 is true, Statement 2 is true and Statement 2 is not the correct explanation of Statement 1.

3. Statement 1 is true and Statement 2 is false.

4. Statement 1 is false and Statement 2 is true.

Q.

Which of the following is/are true?

1. Thrust is a force normal to a surface

2. Pressure is defined as thrust by area

3. Thrust is a vector

4. Thrust is a scalar

Q. Identify the phenomenon common to the following pictures.

1. 
2. 
3. 
4. 

Q.

Explain why, the tip of a sewing needle is sharp.

Q. The same amount of pressure is applied to two different objects with different surface areas. In this scenario, which of the following statements is correct?

1. Both the surfaces experience the same force.
2. The object having more surface area experiences more force.
3. The object having less surface area experiences more force.
4. The object having more surface area experiences less force.

Q.

Statement 1: For the same force acting on two different surfaces, more pressure is developed on the surface with a smaller area.
Statement 2: Pressure is defined as force per unit area.

1. Both the statements are true and statement 2 is the correct explanation of statement 1.

2. Both the statements are true and statement 2 is not the correct explanation of statement 1.

3. Statement 1 is true and statement 2 is false.

4. Statement 1 is false and statement 2 is true.