Answer:
Explanation:
The fact is that there exists no temperature change until a phase change is complete. That is to say, during a phase change, the energy that will be supplied is used only to separate the molecules. There is no part of it is used to increase the kinetic energy of the molecules. So its temperature will not rise, not really, since the kinetic energy of the molecules remains the same. Also, it should be noted that the average kinetic energy of the molecules does not change at the moment that melting occurs, thus the temperature of the molecules does not change.
Answer:
0.050V
Explanation:
To solve this problem it is necessary to use the concepts related to the potential between two objects that have a magnetic field, this concept is represented in the equation.
Where,
v= tangencial velocity
B = Magnetic Field
We know for definition that,
Where,
L = length
Angular velocity
We can replace this values in our first equation then,
Integrating we have,
Replacing the values,
Therefore the potential difference between the center of the rod and the other rod is 0.050V
Answer:
Explanation:
Let's use Ohm's law:
or
(1)
Where:
We know the value of the voltage V, so we need to find the value of R in order to find I. Fortunately there is a relation between the resistivity of a conductor and its electrical resistance given by:
(2)
Where:
Keep in mind that the electrical resistivity of the gold is a known constant which is 
and the cross sectional area of the conductor is calculated as:
Because we have a wire in this case, so we assume a cylindrical geometry.
Now replacing our data in (2)
Finally, we know R and V, so replacing these values in (1) we will be able to find the current:
Answer:D
Explanation:
When the character falls off from cliff he moves away from the observer as he falls down and hence the frequency heard by observer lowers as he falls.
Therefore the pitch of the sound is lower than the original sound and decreasing as he falls
Option D is the correct choice
Answer:
Explanation:
During the first .8 s , the elevator is under acceleration . It starts from initial velocity u = 0 , final velocity v = 1.2 m /s , time = .8 s
v = u + at
1.2 = 0 + .8 a
a = 1.2 / .8
= 1.5 m /s²
During the acceleration in upward direction , let reaction force of ground on man be R .
Net force on man = R - mg
Applying Newton's 2 nd law
R - mg = ma
R = m ( g + a )
= 72 ( 9.8 + 1.5 )
= 813.6 N .
This reaction force will be measured by spring scale , so reading of spring scale will be 813.6 N .
