Important Points to remember:
- Deforming forces are external force applied on a body to change its size or shape.
- Restoring force is the internal force developed in a body trying to bring it back to the original configuration when it is acted upon by an external force trying to change its size or shape.
- Elasticity is the property of a body by virtue of which it tries to regain its original configuration when the deforming forces are removed.
- Perfectly elastic body is a body which regains its original configuration completely on removal of deforming forces.
- Plasticity is the property of a body by virtue of which it does not regain its original configuration on removal of deforming forces.
- Perfectly plastic body is a body which does not show any tendency to regain its original configuration on removal of deforming forces
- Stress: The restoring force developed per unit area of a deformed body is called stress.
- Tensile stress: If a deforming force is trying to produce an increase in length, then the restoring force developed per unit area of cross section is called tensile stress
- Compressive Stress: When a deforming force acting normal to a surface tries to produce a change in volume, then the restoring force produced per unit area is called compressive stress.
- Shearing stress: When a tangential force tries to change the shape of a body whose bottom is fixed, then the restoring force developed per unit area is called Shearing stress.
- Strain: The ratio of the change in dimension to the original dimension of a deformed body is called strain
- Linear or longitudinal strain
HIGHER ORDER THINKING SKILLS
FOOD: Where does it come from.
1. You are the manager of a restaurant, make a list of food items you would serve in lunch.
2. What measures are to be taken to avoid wastage of food.
3. Why are humans considered omnivores?
4. List the ingredients of any five food items you relish.
5. Form pairs of words in group A with words in group B.
A—Mustard plant, Nectar, Beetroot, carnivore, omnivore.
B– Honey, sugar, oil, humans, tiger.
6. Name two aquatic plants eaten as food.
COMPONENTS OF FOOD
1. Why is it necessary to have fresh and un-cooked vegetables and fruits in our diets.
2. Doctors advice us to drink atleast two litres of water daily why?
3. What happens Read more…
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Download a good collection of questions from Class 8 Science NCERT Textbook. The collection includes questions requiring Higher order thinking skills (HOTS
As per request from numerous student visitors, we are publishing some previous question papers used in the previous years. You can use them to prepare for the present exams and score better marks. The previous question papers give a hint on the type of questions. Practice the questions below to check your timing.