Give reasons for the following statements(any five):- 1×5=5
a. School bags are provided with wide straps to carry them.
b. A sharp knife cuts vegetables and fruits more effectively than a blunt knife.
c. Airplanes have pressurized cabins for passenger safety while flying high in the
atmosphere.
d. It is easier to push a lighter box than a similar heavy box on the same floor.
e. Sportsmen use shoes fitted with spikes.
f. Ball-bearing are used in machines.
g. Sports cars, aeroplanes and boats are designed to have a streamline
Answers
Answer:
a. Because the school bag produce the more weight and reduce the pressure in shoulder of the students shoulder.
b. A sharp knife cut the every object are very better because the force of our hand fall over a sharp small area the object producing the large pressure. A knife has a thinker edge does not cut easily.
c. Because the air is a very thin at the altitude the fly.most commonical airplane fly at around 30000 to 40000 feet above sea level. At high altitudes such as this , this is thinner than it is to the ground.
d. It is a force of friction the lighter box are move faster but the havier box are more force than lighter box .
e. sportsman use shoes with spikes to increase the force of friction between the shoes and the ground. The increase froce of friction give them a better grip while running.
f. Ball bearing can sport moderate radial load moderate axial load .