Physics · Mechanical Properties Of Fluids · NEET
No. Force is the total push or pull on a body, measured in newtons (N). Pressure is how much of that force acts on each unit of area, measured in pascals (Pa). The link is Pressure = Force / Area. You can have a small force give large pressure if the area is very small (a needle), or a large force give small pressure if the area is very large (a wide plank).
NCERT gives this exact example. The needle tip touches skin over a very tiny area, so Pressure = Force / Area becomes very large and the skin breaks. The back of a spoon touches over a wide area, so the same force is spread thin and the pressure stays low. The force is equal in both cases; only the contact area differs. Smaller area means greater pressure means greater impact.
Pressure is inversely proportional to area when force is fixed: P = F/A. Halve the area and the pressure doubles. Make the area ten times smaller and pressure becomes ten times larger. This is why a circus performer lies on a wide plank so an elephant's weight (large force) spreads over a large area and gives low, safe pressure on the chest.
Force has a direction, so it is a vector. Pressure in a fluid at rest is a scalar: it has no single direction because a fluid pushes equally in all directions at a point. NCERT clarifies that pressure is the component of force NORMAL (perpendicular) to the surface divided by area, and no direction can be assigned to it, so pressure is not a vector.
They all reduce the contact area. A sharp edge or point has a very small area, so even a modest force produces very high pressure at the tip. That high pressure cuts, pierces or drives the nail in. A blunt tool spreads the same force over a larger area, so the pressure is too low to cut.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Pressure = Force / Area, written P = F/A. Here F is the force normal (perpendicular) to the surface in newtons, A is the area in square metres, and P is pressure in pascals (Pa).
Force is measured in newtons (N). Pressure is measured in pascals (Pa), where 1 Pa = 1 N/m2. So pressure is force per unit area.
Yes. If the area is very small, even a small force gives large pressure because P = F/A. This is exactly why a light push on a needle can pierce the skin.
No. In a fluid at rest pressure is a scalar. It acts equally in all directions and has no assigned direction, so it is not a vector. Force, however, is a vector.
The wide plank spreads the elephant's large weight (force) over a large area. Since P = F/A, a large area makes the pressure small enough for the ribs to stay safe. Without the plank, the small hoof area would give crushing pressure.
