Pressure on a surfacePressure on a surface

P = Normal force / areaP = Normal force / area Unit: NmUnit: Nm-2-2 S.I. unit: Pascal (Pa)S.I. unit: Pascal (Pa) Scalar quantityScalar quantity Normal force

P = force / surface area in contactP = force / surface area in contact P = weight / base areaP = weight / base area

Area Increase, Pressure decreaseArea Increase, Pressure decrease Area decrease, Pressure increaseArea decrease, Pressure increase

θθF Fcosθθ

P = Fcosθθ / Area / Area

Application of Application of Pressure in our Pressure in our

daily lifedaily life

Area Increase, Pressure Area Increase, Pressure decreasedecrease

Snow shoes – broad base to reduce Snow shoes – broad base to reduce pressure – prevent sinking into the pressure – prevent sinking into the snow.snow.

Large elephant leg – able to walk on Large elephant leg – able to walk on muddy ground without sinkingmuddy ground without sinking

Tractor’s tyre Tractor’s tyre

Broad based foundation of buildingBroad based foundation of building

Area decrease, Pressure Area decrease, Pressure increase increase

Knife, scissors, nail, thumbtacksKnife, scissors, nail, thumbtacks Ice skating bootIce skating boot

Foot ball boots with studsFoot ball boots with studs

Woodpecker – sharp beak enable it Woodpecker – sharp beak enable it to pierce and chip tree barkto pierce and chip tree bark