Answer:

Explanation:
initially the merry go round is at rest
after 6.73 s the merry go round will accelerates to 20 rpm
so final angular speed is given as



so final tangential speed is given as


now average acceleration of the girl is given as



Answer:
The correct answer is 
Explanation:
The formula for the electron drift speed is given as follows,

where n is the number of of electrons per unit m³, q is the charge on an electron and A is the cross-sectional area of the copper wire and I is the current. We see that we already have A , q and I. The only thing left to calculate is the electron density n that is the number of electrons per unit volume.
Using the information provided in the question we can see that the number of moles of copper atoms in a cm³ of volume of the conductor is
. Converting this number to m³ using very elementary unit conversion we get
. If we multiply this number by the Avagardo number which is the number of atoms per mol of any gas , we get the number of atoms per m³ which in this case is equal to the number of electron per m³ because one electron per atom of copper contribute to the current. So we get,

if we convert the area from mm³ to m³ we get
.So now that we have n, we plug in all the values of A ,I ,q and n into the main equation to obtain,

which is our final answer.
Answer:

Explanation:
Given two mass on an incline code
and
and an angle of inclination
.
. Assume that
is the weight being pulled up and
the hanging weight.
-The equations of motion from Newton's Second Law are:
where a is the acceleration.
#Substituting for
(tension) gives:

#and solving for 
which is the system's acceleration.
Answer:
Ionic compound.
Explanation:
812° C is a very high melting point. Such high melting points are generally ionic compound. Ionic compounds are have very strong bond between the elements ( electrostatic bond). In order to break this bond, large amount of heat energies are needed. So, they have high melting point. Also, Ionic compound are very good conductors of electricity.
Answer:
The change in potential energy is 
Explanation:
From the question we are told that
The magnitude of the uniform electric field is 
The distance traveled by the electron is 
Generally the force on this electron is mathematically represented as
Where F is the force and q is the charge on the electron which is a constant value of 
Thus


Generally the work energy theorem can be mathematically represented as

Where W is the workdone on the electron by the Electric field and
is the change in kinetic energy
Also workdone on the electron can also be represented as
Where
considering that the movement of the electron is along the x-axis
So

substituting values


Now From the law of energy conservation
Where
is the change in potential energy
Thus
