Thrust & Pressure

Q.

How does the atmospheric pressure change with altitude?

1. Altitude increases, pressure decreases

2. Altitude decreases, pressure decreases

3. Altitude increases, pressure increases

4. Altitude is independent of pressure

Q.

Explain why, school bags are provided with wide straps to carry them.

Q.

Define pressure and give its SI units.

Q.

Define thrust. What is its unit?

Q.

Why does a sharp knife cut objects more effectively than a blunt knife ?

Q.

What does the term force per unit area called?

Q.

A block of wood weigh 4 N in air and 3N when immersed in a liquid. Find out the upthrust acting on it.

Q.

When a balloon is inflated by blowing air into it, the

1. temperature inside the balloon increases

2. air pressure inside the balloon increases

3. humidity inside the balloon decreases

4. density inside the balloon decreases

Q.

State whether pressure is a scalar or vector ?

Q.

Which of these is not a pointing device?

1. Keyboard

2. Mouse

3. Joystick

4. Finger tracking

Q.

Force per unit area is called.

1. Upthrust.

2. Buoyant force.

3. gravity.

4. Pressure.

Q. Why will a sheet of paper fall slower than one that is crumpled into a ball?

Q.

Define one pascal.

Q. When a paper is put in a bucket of water, it floats. This is because density of paper is less than the density of water. However, if it is forced to the bottom, it does not return to the top. If the paper has less density, shouldn't it just float back to the top? Does this mean the paper is just floating because of surface tension and it has nothing to do with density and buoyancy?

Q.

A hammer exerts a force of 1.5 N on each of the two nails A and B. The area of cross section of tip of nail A is 2 $m{m}^2$ while that of nail B is 6 $m{m}^2$. Calculate pressure on each nail in pascal.

Q. a block of lead has dimensions of 4.50cm by 5.20cm by 6.00cm. the block weighs 1587g. from this information, calculate the density of lead in g/cm^3

Q.

Calculate the pressure developed by a force of $50\mathrm{N}$ acting on an area of $10{\mathrm{m}}^2$.

Q.

Explain why, a wide steel belt is provided over the wheels of an army tank.

Q. The pressure exerted on a table, when a cube of side 10 cm and mass 5 kg is kept on it, will be

1. 49 kPa
2. 4.9 kPa
3. 490 kPa
4. 
   0.49 kPa

Q.

Why is drawing pin broad on one end as compared to other end? Explain.

Q.

Why does a camel have broad feet ?

Q.

Why do camesl have large flat feet?

Q.

Why knife have sharp edges

Q. A rectangular wooden block has mass of 4 kg. The length, breadth and height of this wooden block are 50 cm, 25 cm and 10 cm, respectively. Find the pressure on the table top:

(a) When the wooden block is kept with its surface measuring $50cm\times 25cm$ on the table.

(b) When the wooden block is kept with its surface measuring $25cm\times 10cm$ on the table.

(Assume: Acceleration due to gravity, $g=10m{s}^{-2}$) [5 MARKS]

Q.

When is the pressure on the ground more-when a man is walking or when a man is standing? Explain.

Q.

What is Pressure?

Q.

Explain why, a nail has a pointed tip.

Q.

State whether thrust is a scalar or vector ?

Q. Question 12
Gravitational force on the surface of the moon is only $\frac{1}{6}$ as strong as gravitational force on the earth. What is the weight in newtons of a 10 kg object on the moon and on the Earth?

Q.

Why is the tip of an allpin made sharp ?