Rick spends four hours researching on the internet and does 1090 J of work. In the process, his internal energy decreases by 2190 J. Determine the value of Q, including the algebraic sign.

Q = -3280J

Explanation:

From the First Law of Thermodynamics, energy cannot be created nor destroyed but it can be converted from one form to another with the interaction of heat. Mathematically, this can be expressed as:

ΔU = Q + W        (i)

Where;

ΔU = total change in internal energy of a system.

Q = heat exchanged between the system and the surrounding

W = work done by or on the system.

If heat is lost into the surrounding, then Q = -ve, else Q = +ve

If work is done on the system, then W = -ve, else W = -ve

=> From the question, Rick is the system and does a work of

W = +1090J  [since Rick does the work, W = +ve]

=>Also, the internal energy decreases by 2190J, therefore,

ΔU = -2190J   [since there is a decrease in internal energy]

Substitute the values of W and ΔU into equation (i) as follows;

-2190 = Q + 1090

=> Q = -2190 - 1090

=> Q = -3280J

Therefore, the value of Q = -3280J

work: w = fd (given)

work done by chet   =50*1 = 50 j

work done by mika =40*2 = 80 j

work done by sara =30*1.5 = 45 j

work done by bill =60*0.5 = 30 j

students in order from the greatest amount of work done to the least is mika> chet> sara> bill

hence option (b) is correct.