Thrust & Pressure

Q.

At what speed, the velocity head of water is equal to the pressure head of $40\text{cm}$ of mercury?

Q.

Why do balloons filled with hydrogen gas move up in the air?

1. Due to the up thrust of air
2. Due to the weight of the balloon
3. Due to the buoyant force
4. Both A and C

Q.

A balloon filled with hydrogen rises in the air. Explain the reason.

Q. A body falling freely from rest covers 7/16 of the total height in the last second of its fall.The height from which it falls is

Q.

Estimate The Change In The Density Of Water In The Ocean At A Depth Of $400m$ Below The Surface. The Density Of Water At The Surface $=1030kg/m^3$ and The Bulk Modulus Of Water $=2\times {10}^{9}n{m}^{-2}$.

Q. What is pressure? Why do solids exert pressure?

Q. An elephant of mass 4000 kg and foot area 250 cm^{​​​​​2} standing on the floor . Assuming that acceleration due to gravity is 10 m/s^{​​​​​​2} , find the pressure exerted by elephant on the floor?

Q.

How does a hot air balloon able to fly in the air, and which force is applied on it?

Q.

When a bunch of feathers and a stone of the same mass are allowed to fall in the air, the ___ will reach the ground first. (stone/feather)

Q.

We know that there is a huge amount of atmospheric pressure on us but we do not experience its effect. Why?

Q.

On what factors does the effect of thrust on a surface depend?

Q.

What is the relation between thrust and pressure ?

Q.

Two rods of same weight and equal length have different thickness. They
are held vertically on the surface of sand as shown below. Which one of
them will sink more? Why?

Q. A body is dropped from height H. The time taken to cover second half of the journey is.

Q.

Thrust and force are the same thing.

1. True

2. False

Q.

In what direction does the upthrust act?

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. Remain the same
3. Decrease
4. None of these

Q.

Calculate the pressure at a depth of 50 m below the surface of the sea. The density of sea water is 1024$kg/m^3$

1. 512000 Pa

2. 51200 Pa

3. 5120 Pa

4. None of these

Q.

How is the thrust related to pressure ?

Q.

A gum bottle rests on its base. If it is placed upside down, how does the 1) thrust, 2) pressure change?

Q.

The ______ exerted per unit area is called pressure.

Q. A cube of side 0.2 m rests on the floor, as shown. Given that the cube has a mass of 50 kg, the pressure exerted by the cube on the floor is _______. (Take g = 10 $Nk{g}^{-1}$)

Q. ntwhen a stone falling from the top of vertical tower has fallen a distance x m, another is let fall from a point y m below the top.If the fall from the rest and reach the ground together, then the height of the tower is.n

Q.

How are force and pressure related to each other give five points?

Q. The drag experienced by a body will be maximum in which of the following media if the speed of the body remains the same in all of them?

1. 
   Vacuum
2. 
   Water
3. 
   Honey
4. 
   Air

Q.

For a given constant pressure, thrust and area both are inversely proportional to each other.

1. False

2. True

Q. A stone is dropped from a rising balloon at a height of 76m above the ground and reaches the ground in 6 seconds. What was the velocity of the balloon when the stone was dropped

Q.

As per the definition of pressure, it is directly proportional to thrust.

1. True

2. False

Q.

what is difference between thrust and pressure?

Q. A force acts on an area to produce a pressure equal to 200 Pa. When both the force and area of contact are reduced to half, the new pressure would be_______.

1. equal to 200 Pa
2. equal to 300 Pa
3. equal to 100 Pa
4. equal to 400 Pa