A bady increases in weight from 5.58 kg to 6.16 kg . How much weight has the bady gained ?

Answer

0.1MJ

Explanation

(a) Numerical calculation. Compile Table 26.19 from the available data. The quantity of heat dissipated in time `trianglet=1s" is "triangleQ_(n)=t_(n)^(2)R trianglet.` The quantity of heat dissipated during the whole time is equal to the sum of the individual quantities of heat:
`triangleQ=triangleQ_(1)+triangleQ_(2)+triangleQ_(9)=(i_(1 av)^(2)+i_(2av)^(2)+i_(9av)^(2))R trianglet= 2580 xx 40 x 1 =1.03 xx 10^(5)J`
(b) Integration. The current according to the low i=5+2t. The quantity of heat is
`Q=underset(0)overset(10)int i^2 R dt=40 underset(0)overset(10)int (5+2t)^(2) dt-20 underset(0)overset(10)int (5+2t)^(2) d (5+2t)=`
`=(20)/3 (5 2t)^(3) underset(0)overset(10)int =(20)/3 (25^(3)-5^(3))=(20 xx 775 xx 20)/(3)=1.03 xx 10^(5)J`
We see that the result of the numerical calculation was accurate.