Why is it difficult to Breathe at Higher Altitudes?

Question : Why is it difficult to breathe at higher altitudes?
Answer : Because of low air pressure at higher altitudes the quantity of air is less, and so also that of oxygen.

Question : Why does ink leak out of the partially filled pen when taken to a higher altitude?
Answer : As we go up, the pressure and density of air go on decreasing. A partially filled pen leak when taken to a higher altitude because the pressure of air acting on the ink inside the tube of the pen is greater than the pressure of the air outside.

Question : On the moon, will the weight of a man be less or more than his weight on the earth?
Answer : The gravity of the moon is one-sixth that of the earth; hence the weight of a person on the surface of the moon will be one-sixth of his actual weight on earth.

Question : Why do some liquids burn while others do not?
Answer : A liquid burns if its molecules can combine with oxygen in the air with the production of heat. Hence, oil burns but water do not.

Question : Why can we see ourselves in a mirror?
Answer : We see objects when light rays from them reach our eyes. As mirrors have a shiny surface, the light rays are reflected back to us and enter our eyes.

Question : Why does a solid chunk of iron sink in water but float in mercury?
Answer : Because the density of iron is more than that of water but less than that of mercury.

Question : When wood burns it crackles. Explain?
Answer : Wood contains a complex mixture of gases and tar forming vapors trapped under its surface. These gases and tar vapors escape, making a crackling sound.

Question : Why do stars twinkle?
Answer : The light from a star reaches us after refraction as it passes through various layers of air. When the light passes through the earth’s atmosphere, it is made to flicker by the hot and cold ripples of air and appears as if the stars are twinkling.

Question : Why is it easier to roll a barrel than to pull it?
Answer : Because the rolling force of friction is less than the dynamic force of sliding friction.

Question : If a feather, a wooden ball and a steel ball fall simultaneously in a vacuum, which one of these would fall faster?
Answer : All will fall at the same speed in a vacuum because there will be no air resistance and the earth’s gravity will exert a similar gravitational pull on all.

Question : When a man fires a gun, he is pushed back slightly. Why?
Answer : As the bullet leaves the nozzle of the gun’s barrel with momentum in a forward direction, as per Newton’s Third Law of Motion, the ejection imparts to the gun an equal momentum in a backward direction.