Answer:
37.42 m/s
Explanation:
We know that apparent frequency, 
is given by
where f is the given frequency in this case 392, V is the speed of sound in air which is given as 343 and 
is the speed of car which is unknown, \bar f is given as 440 Hz
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.
<span>The amount of heat energy needed to increase the temperature of a substance by </span>
<span> is given by:
</span>
<span>
where m is the mass of the substance, Cs is its specific heat capacity and </span>
<span> is the increase in temperature of the substance.
In this problem, we have a certain mass m of gold, with specific heat capacity </span>
<span>, to which we add Q=2825 J of energy. Its temperature increases by </span>
<span>. Therefore, if we re-arrange the previous equation, we can find the mass of the block of gold:
</span>
<span>
So, the correct answer is B.</span>
