1. The physical quantity expressed by the unit N/m² is
A) Force
B) Pressure
C) Area
D) Intensity
2. Which of the following is not true about Fluid Friction
A) Fluid Friction depends on Shape of the object moving
through fluid
B) It varries with Density of fluid
C) It changes with Density of object
D) Fluid Friction depends on Speed of the object
E) None of these.
3. Which of the following is not true.
A) Liquid pressure is same in different points at a particular
level.
B) Liquid pressure depends on the shape of the container.C) Fluid pressure varies with g.
D) Pressure applied at a particular point in confined liquid
transmitted in all directions.
4. The characteristics of sound related to frequency is
A) Loudness
B) Pitch
C) quality or timbre
D) Both B). & C)
Name the following:.
5. The distance between two consecutive crest or trough in a
wave.
6. The device is used in wheel and axle arrangement to reduce
friction and increase the motion.
please answer this all quickly
Answers
Answer:
Another interesting force in everyday life is the force of drag on an object when it is moving in a fluid (either a gas or a liquid). You feel the drag force when you move your hand through water. You might also feel it if you move your hand during a strong wind. The faster you move your hand, the harder it is to move. You feel a smaller drag force when you tilt your hand so only the side goes through the air—you have decreased the area of your hand that faces the direction of motion. Like friction, the drag force always opposes the motion of an object. Unlike simple friction, the drag force is proportional to some function of the velocity of the object in that fluid. This functionality is complicated and depends upon the shape of the object, its size, its velocity, and the fluid it is in. For most large objects such as bicyclists, cars, and baseballs not moving too slowly, the magnitude of the drag force FD is found to be proportional to the square of the speed of the object. We can write this relationship mathematically as
F
D
∝
v
2
. When taking into account other factors, this relationship becomes
F
D
=
1
2
C
ρ
A
v
2
, where C is the drag coefficient, A is the area of the object facing the fluid, and ρ is the density of the fluid. (Recall that density is mass per unit volume.) This equation can also be written in a more generalized fashion as FD = bv2, where b is a constant equivalent to 0.5CρA. We have set the exponent n for these equations as 2 because, when an object is moving at high velocity through air, the magnitude of the drag force is proportional to the square of the speed. As we shall see in a few pages on fluid dynamics, for small particles moving at low speeds in a fluid, the exponent n is equal to 1.