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Gravity or gravitational force is a form of force. We can describe gravity as the Earth’s magnetic pull. We know about magnets and their attractive force termed magnetic force. Our planet Earth also behaves in ways similar to a magnet and the attractive force produced by Earth due to its magnetic properties is known as Gravity or Gravitational force. This force pulls everything towards the center; hence, we can walk and drive and do other things on Earth’s Crust. Gravity is very important because:

1) It prevents all objects from floating in space and pulls everything towards Earth’s crust or in other words, it is due to the Earth’s gravitational pull that all things on Earth are firmly fixed in their place.

2) We need the help of gravity for everything, say, driving a car, building a wall, etc.

3)Space has no gravity and hence everything in space levitates. It’s the Earth’s and The Sun’s attractive force that fixes Earth into an orbit.

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2. Three types of renewable energy and their role in the reduction of environmental pollution.

Renewable energies are those kinds of energy that are replenished easier. It does not mean that the sources are not exhausted but it means that it replenishes at a faster rate than its usage. Three examples of renewable energy could be: Solar energy, Wind energy, and Tidal Energy

Role in reduction of pollution :

i) They are sources to produce electricity hence preventing the production of electricity from fossil fuels, which is a source of pollution.

ii) Their production does not require any mechanisms that generate wastes that pollute air, water, or soil.

iii) These energy sources can replace the combustion of fossil fuels in vehicles, and act as fuels which in turn reduces air pollution and promotes sustainable development.

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Digestion

The process of digestion starts with the intake of food through the mouth. In the mouth, the teeth and tongue help to grind and mix the food with saliva and other digestive enzymes produced by the various glands present. The food is then swallowed and carried to the stomach through a hollow, muscular, pipe known as the food pipe or esophagus. In the stomach, the food is further churned and broken and mixed with various acids and enzymes. The Hydrochloric acid and the mucus lining present in the stomach kills any bacteria and prevents any damage that could happen to the system through the food. The food is then transported to the small intestine. Inside the small intestine, there are small finger-like structures enriched with blood vessels, called villi. They absorb all the nutrients from the food that was broken down by the stomach. It proceeds towards the large intestine where water is re-absorbed. It is stored in the rectum and is ejected out through the anus from time to time.