You are Here: Home

specific heat capacity: physics watch

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.

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.
3. any help is better than none! thanks
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?
5. becasue of the 2 *C temperature rise.

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.
7. rate of absorbtion of energy has to be in joules per second.
8. Nope

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

Says so in the marks scheme
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)

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: February 1, 2005
Today on TSR

University open days

Wed, 21 Nov '18
• Buckinghamshire New University
Wed, 21 Nov '18
• Heriot-Watt University