# specific heat capacity: physics

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#1
A heating coil is usedx to warm water that flows past it at a steady rate of 0.24 kgs-1. The heating coil remains at a constant working temperature of 350 degrees. the cold wtaer enters at 17 degrees and leaved at 19 degrres. The specific capacity of water is 4200 J kg-1K-1. Calculate the rate of absorption of energy by the cold water assuming no energy is lost to the surroundings.

0
15 years ago
#2
energy supplied to substance = mass * change in temp. * specific heat capacity

You want the rate of absorption of energy, ie the amount of energy per secound supplied. You have the mass in terms of mass per s so you just need to multiply them I think.

0.24*4200*2
=2016JS^-1

however dont trust me totally on this as its a year since I did any work on specific heat capacity.
0
#3
any help is better than none! thanks
0
#4
(Original post by Speciez99)
energy supplied to substance = mass * change in temp. * specific heat capacity

You want the rate of absorption of energy, ie the amount of energy per secound supplied. You have the mass in terms of mass per s so you just need to multiply them I think.

0.24*4200*2
=2016JS^-1

however dont trust me totally on this as its a year since I did any work on specific heat capacity.

why do i need to mulitply it by 2 though?
0
15 years ago
#5
becasue of the 2 *C temperature rise.
0
15 years ago
#6

H/s = m/s c delta T

therefore H = 0.24 kg x 4200 J kg-1K-1 x (2 Kelvin)

H = 2016 Joules

Notice the seconds cancel out and your final answer is in joules.
0
15 years ago
#7
rate of absorbtion of energy has to be in joules per second.
0
15 years ago
#8
Nope

You have to cancel out the seconds and have it in only joules.

Says so in the marks scheme
0
15 years ago
#9
let R = rate of absorbtion of energy

E = m.c.T

R = E/s = m/s.c.T

you do not cancel out the seconds, because you are looking for E and not H.

the mark scheme is wrong (or confused)
0
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