Question

Give reasons for the following statements-
(a) 'Snow shoes' are more effective than ordinary shoes for walking on
snow.
(b) Porters place a large round piece of cloth on their heads when they
carry heavy loads.
(c) A sharp knife cuts vegetables and fruits more effectively than a blunt
knife.
(d) School bags are provided with wide straps to carry them.
(e) It is much easier to burst an inflated balloon with a needle than
(directly) with the finger.
( Mountaineers may suffer from nose bleeding at high altitudes.
(g) Airplanes have pressurised cabins for passenger safety while flying high
in the atmosphere.
​

Answer 1

(A) Snow shoes increase grip and prevent you from slipping and falling.

(B) Porters place cloth around their head to distribute the weight evenly across their head, to make it easier to carry.

(C) Sharp knife applied force in a very small area. Since P=F/A, the pressure is increased in case of a sharp knife.

(D) Wider straps increase surface area and hence decrease the pressure in shoulders.

(E) Same reason. Needle applied force at almost a single point, leading to much larger pressure on the ballon.

(F) Air Pressure decreases with altitude on earth. Our blood vessels apply pressure in opposite direction to Atmospheric pressure to prevent us from being crushed.