Answer:
Because of the speed of the sound.
Explanation:
The first thing that happens in such cases is to take into account the speed of the sound. First, we see that the player hits the ball with the bat, if we are in the stands far enough we will hear the sound of the batting time later, this time depends on the speed of the sound which is equal to 345 [m/s].
Another visible and practical example is a fireworks display, where people nearby immediately hear the explosion. while those at a great distance will be able to see first the explosion followed by the sound.
With the following equation, we can calculate how long it takes to hear a hit or explosion
t = x / v
where:
x = distance [m]
v = sound velocity = 345 [m/s]
t = time [s]
<u>Answer:</u>
Submarines use a device called Periscope that uses the concept of multiple reflections and help us see objects above the water surface.
<u>Explanation:</u>
When a light ray falls on a reflecting surface like a mirror, it gets reflected. In multiple reflections, the incident light ray is made to reflect multiple times by arranging the reflecting surfaces in different ways.
In submarines, we use Periscope, which is a long tube like structure. The long tube is bent at ends. It uses two simple mirrors which are placed parallel to each other at an angle of 45 degrees. The light from one mirror gets reflected to the other mirror, thus causing a multiple reflection.
Answer:
D.None of these
Explanation:
The derivation of acceleration formula:
Let us call the 5kg mass 
and the 4kg mass 
. If the tension in the string is 
then for the mass
(1). 
<em>(the negative sign on the right side indicates that acceleration is downwards)</em>
And for the mass
(2). 
<em> (the acceleration is upwards, hence the positive sign)</em>
Solving for in the 2nd equation we get:
,
and putting this into the 1st equation we get:
Back to the question:
Using the formula for the acceleration we find
which is the acceleration that none of the given choices offer. Also, the acceleration of the two blocks is the same, because if it weren't, the difference in the instantaneous velocities of the objects would cause the string to break. Therefore, these two reasons make us decide that none of the choices are correct.
The right answer for the question that is being asked and shown above is that: "B) allowing Carolina planters to expand rice cultivation into Georgia's lowlands."
-I hope this is the answer you are looking for.
Answer:
a)W= - 720 J
b)ΔU= 330 J
Explanation:
Given that
P = 0.8 atm
We know that 1 atm = 100 KPa
P = 80 KPa
V₁ = 12 L = 0.012 m³ ( 1000 L = 1 m³)
V₂ = 3 L = 0.003 m³
Q= - 390 J ( heat is leaving from the system )
We know that work done by gas given as
W = P (V₂ -V₁ )
W= 80 x ( 0.003 - 0.012 ) KJ
W= - 0.72 KJ
W= - 720 J ( Negative sign indicates work done on the gas)
From first law of thermodynamics
Q = W + ΔU
ΔU=Change in the internal energy
Now by putting the values
- 390 = - 720 + ΔU
ΔU= 720 - 390 J
ΔU= 330 J
