Advertisements
Advertisements
Question
If someone presses a pointed needle against your skin, you are hurt. But if someone presses a rod against your skin with the same force, you easily tolerate. Explain.
Advertisements
Solution
We know that pressure is the application of force over a particular area. In mathematical terms, pressure is equal to force divided by area; that is, with more force comes more pressure and with more area comes less pressure. An iron rod has more surface area than the pointed tip of a needle. That is why the pointed needle exerts more pressure than the iron rod (with the same force) when pressed against our skin.
APPEARS IN
RELATED QUESTIONS
Explain why The blood pressure in humans is greater at the feet than at the brain
Toricelli’s barometer used mercury. Pascal duplicated it using French wine of density 984 kg m–3. Determine the height of the wine column for normal atmospheric pressure.
For a given thrust, pressure is more on a surface of large j area.
The pressure on a surface increases with an increase in the thrust on the surface.
It is easier to hammer a blunt nail into a piece of wood than a sharply pointed nail.
Water in a lake exerts pressure only at its bottom.
1 kgf = .............. (nearly).
The feet of lizards act like
Name two factors on which the pressure on a surface depends.
A gum bottle rests on its base. If it is placed upside down, how does the thrust change?
A boy weighing 60 kgf stands on platform of dimensions 2.5 cm x 0.5 cm. What pressure in pascal does he exert?
Water flows through a horizontal tube of variable cross section. The area of cross section at A and B are 4 mm2 and 2 mm2 respectively. If 1 cc of water enters per second through A, find (a) the speed of water at A, (b) the speed of water at B and (c) the pressure difference PA − PB.
An empty plastic bottle closed with an airtight stopper is pushed down into a bucket filled with water. As the bottle is pushed down, there is an increasing force on the bottom. This is because
A chapatti maker is a machine which converts balls of dough into chapatties. What effect of force comes into play in this process?
Pressure can be increased by decreasing the force.
Cooking in a place located at a higher altitude is difficult. Why?
Give reasons why:
a single nail pricking the body is painful when compared to lying on a bed of nails.
It is easy to compress a gas whereas liquids are ______.
The shape and size of the solids do not easily change.
