Answer: send the message underwater because a more dense medium would make the sound travel faster.
Explanation:
Dolphins communicate using compression waves - longitudinal waves. Longitudinal waves requires a medium to travel. A longitudinal wave transfers energy by the vibration of medium particles in the direction of the wave motion. Compression are the regions where density of the medium is higher and rarefaction is a low density region.
A longitudinal wave travels faster in a denser medium. It has maximum speed in solid and minimum in gas. Thus, to transfer message quickly to dolphin B., dolphin A should send the message underwater and not in air. This is because water has higher density than air. Molecules collide more quickly in water than in air and it takes less time for signal to travel.
The answer is false. The speed of the astronaut cancels out the force of gravity, causing a 'stationary freefall'. While under these effects, it is not required for an astronaut to 'strengthen' his body.
Answer:

Explanation:
<u>2-D Projectile Motion</u>
In 2-D motion, there are two separate components of the acceleration, velocity and displacement. The horizontal component has zero acceleration, while the acceleration in the vertical direction is always the acceleration due to gravity. The basic formulas for this type of movement are






The projectile is fired in such a way that its horizontal range is equal to three times its maximum height. We need to find the angle \theta at which the object should be launched. The range is the maximum horizontal distance reached by the projectile, so we establish the base condition:


Using the formulas for 

Simplifying

Dividing by 

Rearranging



<u>Answer:</u> The number of electrons in given amount of silver are 
<u>Explanation:</u>
To calculate the number of moles, we use the equation:

We are given:
Given mass of silver = 7.1 g
Molar mass of silver = 107.87 g/mol
Putting values in above equation, we get:

Number of electrons in 1 atom of silver = 47
According to mole concept:
1 mole of an element contains
number of particles
So, 0.066 moles of silver will contain = -
number of electrons
Hence, the number of electrons in given amount of silver are 