Thrust & Pressure

Q.

What is the unit of pressure?

1. 

2. 

3. Nm

4. 

Q.

How is thrust different from pressure?

1. Thrust is the force per unit area but pressure is the force perpendicular to that area

2. Pressure is the force per unit area but thrust is the force perpendicular to that area

3. Both are same

4. None of these

Q.

The SI unit of pressure and thrust are respectively:

1. N/m²

2. N/m

3. Nm

4. N²/m

Q. A feather and a coin released simultaneously do not reach the ground at the same time because of

1. none of these
2. resistance of air
3. force of gravity
4. difference in mass

Q. The upward force acting on an object submerged in a liquid is called:

1. Magnetic force
2. Gravitational force
3. Frictional force
4. Buoyant force

Q.

Calculate the pressure at a depth of $50m$ below the surface of the sea. (The density of sea water is $1024kg{m}^{-3}$).

1. $512000Pa$

2. $51200Pa$
3. $5120Pa$
4. $512Pa$

Q. A balloon of mass `m’ is rising with an acceleration `a’. A fraction of its mass is detached from the balloon. Its acceleration will

1. Increase
2. None of these
3. Remain the same
4. Decrease

Q. A piece of the iron nail when kept horizontally on the surface of the sand, rests on it but when kept vertically digs a small hole. Why does this happen?

1. Due to less pressure
2. Due to increased weight
3. Due to reduced weight
4. Due to more pressure

Q. Pressure ${\text{P}}_1$ is applied on a sphere of radius $5\text{cm}$. Keeping the thrust constant, if the radius of the sphere is decreased to $2.5\text{cm}$, the new pressure is found out to be ${\text{P}}_2$. Find ${\text{P}}_2:{\text{P}}_1$.

1. 4

Q. Increase in height of mercury column indicates:

1. decrease in atmospheric pressure
2. increase in atmospheric pressure
3. no change in atmospheric pressure
4. increase in humidity in air

Q. The resultant of the weight of a body and the upthrust when it is submerged in a liquid acts at a point called:

1. Centre of gravity
2. Geometric centre
3. Centre of buoyancy
4. None of the above