The frictional force exerted by fluids is also called drag or fluid friction. To overcome or minimize air fluid friction, the bodies of objects minimise its surface i.e. sometime spherical shapes or other streamlined shape with smooth surface. Aeroplanes, jets, rain drops have streamlined curve surfRead more
The frictional force exerted by fluids is also called drag or fluid friction. To overcome or minimize air fluid friction, the bodies of objects minimise its surface i.e. sometime spherical shapes or other streamlined shape with smooth surface. Aeroplanes, jets, rain drops have streamlined curve surface to reduce air drag.
Friction is both a friend and a foe due to following reasons: Friction act as friend: • We are able to walk because of frictional forces between ground and our feet. • We are able to write because of friction between ball point and the paper surface. • Nails and screws stick to wall surfaces becauseRead more
Friction is both a friend and a foe due to following reasons:
Friction act as friend:
• We are able to walk because of frictional forces between ground and our feet.
• We are able to write because of friction between ball point and the paper surface.
• Nails and screws stick to wall surfaces because of friction.
• Lighting a match stick is because of friction between match stick and the side surface of match box.
Friction act as foe:
• Wear and tear of soles of our shoes is due to friction.
• When a tyre deflates, it is difficult to move the vehicle because of increased friction between the tyre and road surface.
• Machines gets heated up because of friction.
• Due to friction, machines and vehicles consumes more fuel and increase maintenance cost.
Friction force is directly proportional to mass. Heavier box will put more force on the floor surface as compared to lighter box and therefore will experience more opposite force (friction). Seema will have to apply larger force. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-Read more
Friction force is directly proportional to mass. Heavier box will put more force on the floor surface as compared to lighter box and therefore will experience more opposite force (friction). Seema will have to apply larger force.
Spikes increase friction and give better grip with the ground. It avoids slipping of sportsmen while playing or running. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-12/
Spikes increase friction and give better grip with the ground. It avoids slipping of sportsmen while playing or running.
It would be difficult to walk on the floor. Soapy water fills the floor irregularities, thus reduces the friction considerably. Feet do not make necessary grip with the floor surface, thus increasing the chances of falling. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-12/
It would be difficult to walk on the floor. Soapy water fills the floor irregularities, thus reduces the friction considerably. Feet do not make necessary grip with the floor surface, thus increasing the chances of falling.
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See lessExplain why objects moving in fluids must have special shapes.
The frictional force exerted by fluids is also called drag or fluid friction. To overcome or minimize air fluid friction, the bodies of objects minimise its surface i.e. sometime spherical shapes or other streamlined shape with smooth surface. Aeroplanes, jets, rain drops have streamlined curve surfRead more
The frictional force exerted by fluids is also called drag or fluid friction. To overcome or minimize air fluid friction, the bodies of objects minimise its surface i.e. sometime spherical shapes or other streamlined shape with smooth surface. Aeroplanes, jets, rain drops have streamlined curve surface to reduce air drag.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-12/
See lessGive examples to show that friction is both a friend and a foe.
Friction is both a friend and a foe due to following reasons: Friction act as friend: • We are able to walk because of frictional forces between ground and our feet. • We are able to write because of friction between ball point and the paper surface. • Nails and screws stick to wall surfaces becauseRead more
Friction is both a friend and a foe due to following reasons:
Friction act as friend:
• We are able to walk because of frictional forces between ground and our feet.
• We are able to write because of friction between ball point and the paper surface.
• Nails and screws stick to wall surfaces because of friction.
• Lighting a match stick is because of friction between match stick and the side surface of match box.
Friction act as foe:
• Wear and tear of soles of our shoes is due to friction.
• When a tyre deflates, it is difficult to move the vehicle because of increased friction between the tyre and road surface.
• Machines gets heated up because of friction.
• Due to friction, machines and vehicles consumes more fuel and increase maintenance cost.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-12/
See lessIqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force and why?
Friction force is directly proportional to mass. Heavier box will put more force on the floor surface as compared to lighter box and therefore will experience more opposite force (friction). Seema will have to apply larger force. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-Read more
Friction force is directly proportional to mass. Heavier box will put more force on the floor surface as compared to lighter box and therefore will experience more opposite force (friction). Seema will have to apply larger force.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-12/
See lessExplain why sportsmen use shoes with spikes.
Spikes increase friction and give better grip with the ground. It avoids slipping of sportsmen while playing or running. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-12/
Spikes increase friction and give better grip with the ground. It avoids slipping of sportsmen while playing or running.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-12/
See lessYou spill a bucket of soapy water on a marble floor accidently. Would it make it easier or more difficult for you to walk on the floor? Why?
It would be difficult to walk on the floor. Soapy water fills the floor irregularities, thus reduces the friction considerably. Feet do not make necessary grip with the floor surface, thus increasing the chances of falling. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-12/
It would be difficult to walk on the floor. Soapy water fills the floor irregularities, thus reduces the friction considerably. Feet do not make necessary grip with the floor surface, thus increasing the chances of falling.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-12/
See lessFour children were asked to arrange forces due to rolling, static and sliding frictions in a decreasing order. Their arrangements are given below. Choose the correct arrangement.
Static, sliding, rolling. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-12/
Static, sliding, rolling.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-12/
See lessAlida runs her toy car on dry marble floor, wet marble floor, newspaper and towel spread on the floor. The force of friction acting on the car on different surfaces in increasing order will be:
(a) Wet marble floor, dry marble floor, newspaper and towel. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-12/
(a) Wet marble floor, dry marble floor, newspaper and towel.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-12/
See lessFour children were asked to arrange forces due to rolling, static and sliding frictions in a decreasing order. Their arrangements are given below. Choose the correct arrangement.
(c) Static, sliding, rolling. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-12/
(c) Static, sliding, rolling.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-12/
See lessSliding friction is ___________ than the static friction.
Sliding friction is lesser than the static friction. https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-12/
Sliding friction is lesser than the static friction.
https://www.tiwariacademy.com/ncert-solutions/class-8/science/chapter-12/
See less