Answer:D) His Facial expressions when they spend time together
Explanation:
Eva's should carefully observe the normal verbal signs by her lover because facial expression gives the hint to listener or viewer that one is interested towards other.
Some common facial Expression are
- Smiling Eyes:While smiling is, of course, an important expression when we speak, attempting to keep a constant smile could make you look more like a trained sociopath than a happy, enthusiastic presenter. These enables other person to feel the good vibes out of you and left a positive impact of your presence.
- Nod on: It is important to express interest in the feedback of your audience. No one likes an identity-centered snob. One way to show that you're actually engaged in the comments and questions they pose is by nodding while you're listening. Moving your head a little wider will help to express your attention as well.
Let the observer be 'd' distance away from the thunderstorm and let light take 't' time to reach the observer
Since the speed of sound and light remains constant in a particular medium, we can use
Speed = Distance/Time
For light,
3 x 10^8 = d/t
t = d/(3 x 10^8) -1
For sound,
339 = d/(t + 30) -2
Putting value from 1 in 2.
d = 10^4 m(approx)
Solar cells and solar panels are both integral, and closely related, parts of a solar energy system. When reading about solar energy systems, it may seem as if these titles are almost interchangeable. Writers refer to them both when discussing energy production and output, and often do so without explanation of how these parts work. However, each plays a distinct role. Solar cells contain all the parts necessary to convert sunlight to electricity. Solar panels combine and direct all of that energy output.
Kinetic and Potential Energy HistoryA roller coaster train going down hill represents merely a complex case as a body is descending an inclined plane. Newton's first two laws relate force and acceleration, which are key concepts in roller coaster physics. At amusement parks, Newton's laws can be applied to every ride. These rides range from 'The Swings' to The 'Hammer'. Newton was also one of the developers of calculus which is essential to analyzing falling bodies constrained on more complex paths than inclined planes. A roller coaster rider is in an gravitational field except with the Principle of Equivalence.Potential EnergyPotential energy is the same as stored energy. The "stored" energy is held within the gravitational field. When you lift a heavy object you exert energy which later will become kinetic energy when the object is dropped. A lift motor from a roller coaster exerts potential energy when lifting the train to the top of the hill. The higher the train is lifted by the motor the more potential energy is produced; thus, forming a greater amount if kinetic energy when the train is dropped. At the top of the hills the train has a huge amount of potential energy, but it <span>has very little kinetic energy.Kinetic Energy The word "kinetic" is derived from the Greek word meaning to move, and the word "energy" is the ability to move. Thus, "kinetic energy" is the energy of motion --it's ability to do work. The faster the body moves the more kinetic energy is produced. The greater the mass and speed of an object the more kinetic energy there will be. Hope this helped:))))</span>
Answer:
The block's mass should be 
Explanation:
Given:
Cart with mass 
From the conservation of energy before mass is added,
Where 
amplitude of spring mass system, 
spring constant
Now new mass 
is added to the system,
Here, given in question frequency is reduced to half so we can write,
Where 
frequency of system before mass is added, 
frequency of system after mass is added.
Therefore, the block's mass should be
