Synthetic Fibres and Plastics — Science STD 8 — Question

How can a very heavy machine be moved conveniently from one place to another in a factory? (No crane is available for this purpose).

How can we prevent the following diseases? Typhoid.

In the following situation, identify the agent exerting the force and the object on which it acts. State the effect of the force in each case.
(a) Squeezing a piece of lemon between the fingers to extract its juice.
(b) Taking out paste from a toothpaste tube.
(c) A load suspended from a spring while its other end is on a hook fixed to a wall.
(d) An athlete making a high jump to clear the bar at a certain height.

Define manure. What are the advantages of manure?

How can a very heavy machine be moved conveniently from one place to another in a factory? (No crane is available for this purpose).

Few days back, Shradha, a student of class VIIIth was driving the car. She went to a crop field. The level of road were just above the level of ploughed field. As she wanted to stop the slow moving car, the brakes failed to work at that time. Suddenly, she turned the car towards the ploughed field. After sometime, the car came to rest.
(a) Shradha turned the car towards the ploughed field. Explain why?
(b) Explain how the car came to rest after covering some distance in the ploughed field?
(c) Mention the values that Shradha exhibits here.

On which periodic phenomenon are the following measures of time based:
(i) day
(ii) month
(iii) year?

Sodium is more reactive than iron. How can you prove it?

John saw full moon on a particular day. After how many days, he will be able to see the full moon again?

Beera, wants to practice crop rotation in his field. Suggest a Rabi crop and a Kharif crop which will replenish his field with nitrogen. Which crop replenishes nitrogen and why?