How many joules are there in one BTU. See data below.?

Question

The British thermal unit (Btu) is commonly used in engineering applications. A Btu is defined as the amount of heat required to raise the temperature of 1 lb of water by 1°F. There are __________ joules in one Btu. 1 lb = 453.59 g; °C = (5/9)(°F - 32°); specific heat of H2O (l) = 4.18 J/g-K.

Answer 1

easy
Q= mcdt m=453.59g c= 4.18J/g-K dt = 5/9
so Q = 453.59*4.18*5/9 =1053.3J

confirmed by my link (The result in the link is slightly higher since the y took more digits for c)

Answer 2

H = mSt
1 B Th U = 1lb * 1 * 1F
= 453.59 gm* 1* 5/9C
= 251.99 cal
=251.99*4.2 J
=1058.3767J