Question

Answer the following: -
1.Give two examples of situation in which applied force causes a change in the
shape of an object.
2. A force of 35N acts over an area of 7 Sq.m Calculate the pressure.
3. Write the correct words by placing letters in correct sequence.
i) Car : Fuel ; body: -
ii) Mass :
; weight : Newton
4. Give the name of a plastic used for making fibres.
5. What are synthetic fibres made of?
6. What are the types of synthetic fibres?
7. What are the advantages and disadvantages of plastics?
8. Rearing honeybees for honey is called
9. Conversion of proteins into ammonia is called
10. Name the nitrogen fixing bacteria in root modules of leguminous plants.​

Answer 1

Answers

1) Two examples of forces that cause a change in the shape of an object are as follows:

Squeezing of a plastic bottle changes the shape of the bottle.

Deformation of clay by pressing it between the hands.

4) thermosetting plastic

5) Synthetic fibers are made from synthesized polymers of small molecules

6) Synthetic fibres are of four types, namely: Rayon. Nylon. Polyester Acrylic.

7) There are many advantages of plastic materials such as:

They are water resistant. They are durable. They are strong. They are economical.

Disadvantages of using ""plastics"" are:

They pollute our environment.

They pose a danger to wildlife.

They do not degrade quickly.

8) apiculture

9) The process of conversion of protein into ammonia is called ammonification .

10) cyanobacteria (or blue green algae

Answer 2

Answer:

1) Squeezing of a plastic bottle changes the shape of the bottle.

   Deformation of clay by pressing it between the hands.

2) Pressure= Force/Area

   So, P= 35/7 which is equal to 5N per square meter.

3) (i) Food

   (ii) Pressure

4) Thermosetting Plastic or Polythene.

5) Synthetic fibers are made from synthesized polymers of small molecules.

6) There are four types of Synthetic fibres, namely:

    Rayon

    Nylon,

    Polyester,

    Acrylic

7) The advantages of Plastics:

    It is durable, low cost, water resistant and are light weight.

    Disadvantages of Plastics are:

    They pollute our environment.

    They pose a danger to wildlife.

    They do not degrade quickly.

     Lesser energy and heavy chemicals requirements in manufacture

8) Apiculture

9) Ammonification

10) Rhizobia bacteria convert nitrogen gas (N2) to ammonia (NH3) in a process called nitrogen fixation.