10 Important Science Questions And Their Scientific Reasons.

10 Important Science Questions And Their Scientific Reasons.

1. Why does a gun recoil when a shot is fired out?

Since the mass of the gun is much greater than that of the bullet; hence the speed of the gun is very small as compared to that of the bullet. Therefore, the gun moves backwards only by a small distance during recoil.

2. Why are passengers thrown in the forward direction when a running bus stops suddenly?

Passengers sitting or standing in a running bus share the motion of the bus. This means, the passengers in a running bus are also moving with the same speed in the same direction. When the running bus stops suddenly, the lower part of the passenger’s body come to rest, while the upper part continues to remain in motion. As a result, the passengers are thrown in the forward direction when a running bus stops suddenly.

3. An iron ball sinks, a ship does not, why?

In case of iron ball, its weight is more than the weight of water it displaces. In case of ships, the space inside being vacant, the weight of the ship is less than the weight of water it displaced. thus, whereas upward thrust is sufficient to balance the weight of the ship, it is inadequate to balance the weight of the ball.

4. Why is driving on a icy highway extremely dangerous?

For safe driving frictional force between the tyres and the road is an essential factor. When these frictional forces become less, the driving becomes difficult. As the force of friction between the tyre and ice is very small, therefore, driving on icy highway on icy highway becomes dangerous.

5. Why is a gap left at the joint between two rails?

A long railway track consists of many sections of steel called rails – joined to each other. While laying a railway line a small gap is left in between two rails at their joint to allow for the expansion during summer. If such a gap is not left at the joints of rails, the track will get deformed due to thermal expansion in summer, which may cause derailment of trains.

      Another method of allowing for the expansion of rails is to use a wedge joint between the two rails. When the temperature rises during summer, the rails expand and their ends side part each other.

6. Why does water get cooled in an earthen pot (surahi or matka)?

As earthen pot has small pores in its walls. When water is poured into it, some of it seeps through these pores to its outer surface. On reaching there, it evaporates. The heat required for evaporation is taken from the earthen pot and from the water in it. As a result, the water in an earthen pot gets cooled down.

7. Explain how bats use ultrasound to catch a prey.

Bats are usually active at night. They search out for their prey at night. They try to detect the ultrasonic waves emitted by them. The high pitched ultrasonic squeaks of the bat are reflected from the obstacle or the prey and returned to bat’s ear. The nature of reflection tells the bat about the location and size of the prey and they are able to easily attack them.

8. Why do diamonds shine at night?

The rays of light entering it get internally reflected from most of the faces, on account of high refractive index so, from a few faces that permit light to get out, a lot of light comes out.

9. Why does a straight stick look bent when partly immersed in water?

When the rays of light enter another medium, they change their path due to refraction, so the stick looks bent, when partly immersed in water.

10. Why does it take some time to see objects in a dim room when you enter the room from bright sunlight outside?

In a dark room, if we try to see objects, the pupil will enlarge itself. So that more light enters it. If one suddenly goes into bright sunlight (or switches the bright light) one feels the glare. This is because too much light enters the enlarged pupil. Generally, the pupil contracts and things begin to appear normally.