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# Points to Remember, Glossary, Concept Map

8th Science : Chapter 2 : Force and Pressure : Points to Remember, Glossary, Concept Map

Points to Remember

• Force acting on a body tends to change its state of rest or of motion or its shape. The SI unit of force is newton.

• Force acts only when two or more objects interact with one other.

• The effect of force can be measured using the physical quantity called pressure.

• Liquids, gases and air also exert pressure.

• All objects on the surface of the Earth experience a constant thrust or force due to the atmosphere.

• Atmospheric pressure can be measured by a device called barometer.

• Friction is the force that opposes the motion of an object.

• Friction is caused by irregularities on the surfaces, which are in contact.

• Friction depends on the nature of the surfaces and mass of the bodies in contact.

• Friction is classified into two types: static friction and kinetic friction. Kinetic friction can be further classified as rolling friction and sliding friction.

• Surface tension is the tendency of liquid surfaces to shrink to have minimum surface area as mush as possible.

• When liquids are flowing there is a frictional force between the layers of the liquid, which oppose their relative motion. This force is called viscous force and the phenomenon is known as viscosity.

• Viscosity is measured by the unit called poise in CGS system and kgm–1s–1 and Nsm–2 in SI.

GLOSSARY

Buoyant force An upward force exerted by liquid on a floating body.

Force - Ation of push or pull.

Friction - Force produced due to the geometrical dissimilarities of the surface of the bodies which are in relative motion.

Pressure - Force acting on unit area.

Surface tension Force which contracts the surface area of the liquids.

Thrust - Force acting perpendicularly on any given surface area.

REFERENCE BOOKS

1. Fundamentals of Physics (English, Hardcover) David Halliday & Jearl Walker.

2. Principles of Physics, International Student Version (English, Paperback) Jearl Walker, David Halliday, Robert Resnick.

3. Concepts of Physics (Volume-1) 1st Edition (English, Paperback) H. C. Verma.

4. Fundamentals of Physics (English, Hardcover) David Halliday

INTERNET RESOURCES

1. h t t p s : / / w w w . y o u t u b e . c o m / watch?v=Oe6bDTL3YQg

2. h t t p s : / / w w w . y o u t u b e . c o m / watch?v=KndNN28OcEI

4.https://www.stufftoblowyourmind.com/videos/51302-stuff-to-blow-your-kids mind-atmospheric-pressure-video.htm

Concept Map

ICT CORNER

Force and Pressure

This activity helps to learn about the Fluid pressure & Pascal’s Law

Steps

* Open the Browser and type the URL link given below (or) Scan the QR Code.

* Select the “Fluid Pressure and Pascal’s Law” .You can view this page.

* To get more idea about the Pascal’s Law for fluid pressure through Experiment.