Both F's are forces, so µ must be unitless/dimensionless.
F[friction] = µ F[normal]
Or, more explicitly in terms of the units:
(Newtons) = (constant) (Newtons)
This occurs due to convection! warm air (and water) rises and the cold sinks!
The relation between electric field intensity, electric force and charge is given as follow,

Where,
F = Force
q = Charge
The direction of force on a charge placed in an electric field is same as the direction of electric field if the charge has positive polarity and opposite if charge has negative polarity.
Replacing we have that


As direction of force is upward and polarity of charge is negative, hence the direction of field will be opposite to that of force. Therefore direction of field is downward.
Since the specific heat of silver is given to be 0.057 calories/gram*C, obtaining the amount of calories should be as easy as multiplying the specific heat by the given values of the weight and the temperature to do unit cancellation. This is shown below:
(<span>0.057 calories/gram*C</span>)(10 grams)(20 C) = 11.4 calories