Answer:
Zero
Explanation:
Given the equation of an ellipse:

The eccentrity of an ellipse is given by:

For a circle, we have

Therefore the eccentricity of a circle is

Answer:
Sound waves are longitudinal in nature.
Explanation:
There are many types of waves like transverse, longitudinal, electromagnetic wave etc.
Sound waves are longitudinal in nature. In longitudinal type of wave, the medium particles moves parallel to the propagation of the wave. This type of waves move in the form of compression and rarefaction.
In compression, the particle density at a point is very less while in rarefaction, the particle density at a point is very high.
So, the correct option is (b) "longitudinal wave".
Answer: Speed
Explanation:
Speed is the time it takes something to travel a certain distance. Accelaration is the rate at which an object's speed changes. Velocity is a vector of the object's speed and direction.
The velocity of the brick is 39.2 m/s downward
Explanation:
The motion of the brick is a free fall motion, since the object is affected only by the force of gravity. Therefore, it has a uniformly accelerated motion towards the ground, with constant acceleration of
.
So, we can find its velocity using the suvat equation:

where
v is the final velocity
u is the initial velocity
a is the acceleration
t is the time
For the brick in this problem (taking downward as positive direction)
u = 0 (it is dropped from rest)

Therefore, its velocity after t = 4.0 s is:

Downward, because the sign is positive.
Learn more about free fall motion:
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