Fluid Friction and Air Resistance
Questions about drag, air resistance, and fluid friction including factors affecting friction, streamlined shapes, and applications in vehicles and objects moving through fluids.
Questions
Fill in the blanks
Dynamic Fluid friction is _______ the sliding friction of solids.
- heigher than
- lower than
- same as
- higher than or equal to
The frictional force exerted by fluids is called:
- lift
- drag
- rolling friction
- dynamic friction
Boats and aeroplanes are ................. so as to reduce fluid friction.fill in the blank.
- large
- broader
- streamlined
- bigger
Fluid friction is exerted by _____ .
- solids and liquids
- solids and gases
- liquids and gases
- all the above
Fluid friction depends on ______
- speed of the object
- shape of the object
- nature of fluid
- all of the above
What measures are taken to reduce fluid friction in aeroplanes?
- Optimum speed is maintained with respect to the air
- Metals are choosen in a way to make the aeroplane lighter with smoother surface
- Streamlined body inspired by birds
- All of the above
To move at same speed, a car with flat face and another with streamlined body, will require different amount of force from the engine. The engine of the streamline bodied car will:
- exert less force
- exert more force
- exert zero force
- exert no force
While the arrow moves towards its target, the force acting on it are due to gravity and due to ____ of air.
- gravitational force
- muscular force
- magnetic force
- frictional force
Driving a car on a highway with windows open reduce the speed. This is due to:
- air resistance
- mechanical defect
- bad driving
- none of these
________________ is a force that resists the movement of a solid object through a fluid.
- Thrust
- Magnetic force
- Fluid friction
- None of these
What is drag ?
- Frictional force offered by fluids
- Friction force offered by a solid surface
- Pulling a body over a surface
- None of these
If we drop a cup of water on a plate and a cup of oil on another plate, water is seen to spread faster along diameter. This is an example related to:
- fluid friction
- rolling friction
- sliding friction
- static friction
- higher than
- lower than
- same as
- higher than or equal to
The deeper we go inside a flowing river, fluid friction:
- decreases
- increases
- remains same
- becomes zero
Which of the following statements indicates advantage of fluid friction?
- Walking on road
- Rolling stone on carpet
- Lubricating machine parts
- None of the above
- higher
- lower
- same
- zero
Hailstones falling from atmosphere relates to:
- static friction
- rolling friction
- sliding friction
- fluid friction
Aeroplanes are streamlined to reduce friction.
- True
- False
Aeroplanes are streamlined to reduce:
- fluid friction.
- sliding friction.
- kinetic friction.
- limiting friction.
Smooth surface produces ----- friction than a rough surface.
- Less
- More
- Constant
- None of these above
The arrow with a pointed tip can move faster in air than that of with a blunt tip.
- True
- False
- Ambiguous
- Data insufficient
State whether the given statement is true or false:
- True
- False
A man of mass $m$ walks from end $A$ to the other end $B$ of a boat of mass $M$ and length $l$. The coefficient of friction between the man and the boat is $ \mu $ and neglect any resistive force between the boat and the water.
- If the man runs at his maximum acceleration, the acceleration of the boat is $ (m/M)g $.
- The maximum time take by the men to reach the other end of the boat is $ \sqrt { \dfrac { 2Ml }{ (M+m)\mu g } } $.
- If the man runs at his maximum acceleration, the acceleration of the boat is $ \dfrac { m }{ m+M } \mu g $.
- The minimum time take by the men to reach the other end of the boat is $ \sqrt { \dfrac { 2ml }{ (M+m)\mu g } } $.