In view of the coronavirus pandemic, we are making LIVE CLASSES and VIDEO CLASSES completely FREE to prevent interruption in studies
Home > Formulas > Physics Formulas > Heat Formula
Physics Formulas

Heat Formula

Heat is the form of energy which is transferred between two substances at different temperatures. The direction of the flow of energy is from the substance of higher temperature to the substance of lower temperature. Heat is usually measured in units of energy i.e. calories or joules. Heat and temperature should not be used interchangeably, but this is incorrect. The temperature will measure the hotness or coldness of a substance. In this article, we will discuss the heat formula with examples. Let us learn the concept!

Heat Formula

What is the concept behind heat?

Heat is the transfer of kinetic energy from one medium to another medium via energy source. This energy transfer can occur in three different ways which are radiation, conduction, and convection. Heat is a form of energy which produces a change in the temperature of any substance.

Also, the temperature is the average kinetic energy per molecule of that substance. Temperature is measured in different scales as Celsius (C), Fahrenheit (F) and Kelvins (K). Therefore, in a simple way temperature is how hot or cold an object is. On the other hand, heat is the energy that flows from a hotter object to a cooler object.

Due to heat thermal expansion may occur. It is a phenomenon that takes place in solids, liquids, and gases. Almost all substances expand with an increase in the temperatures. For example, due to the heating of air in a hot air balloon, the balloon expands and rises. In every case, thermal expansion occurs in response to the increase in temperature and devices may take advantage of this concept.

Heat by conduction takes place when two objects are kept in direct contact. Also, the temperature of one is higher than the other. The temperature tends to equalize and due to which the heat conduction consists of the transfer of kinetic energy from warmer medium to a cooler one.

We denote heat is denoted by Q.

The Heat formula is:

C = \(\frac{Q}{m\Delta T}\)

Where,

C specific heat,
m mass of the body,
\(\Delta\) temperature difference.

We generally use Heat formula to find out the heat transfer, mass, specific heat or temperature difference in a given situation. Heat is expressed in units of Joules (J).

Solved Examples

Q.1: Determine the heat needed to raise a 1 kg of iron from 250° C to 600° C?

Solution:

As given in the problem,

Mass, m = 1 Kg,

Specific heat of iron, C = 0.45 \(Jg^-1°C \)

Also, temperature difference,

\(\Delta T = 700° C – 250° C \)

\(\Delta T = 450° C \)

Now applying the heat formula,

\(c = \frac{Q}{m\Delta T} \)

rearranging the formula

\(Q = mc\Delta T \)

\(Q = 1 \times 0.45 \times 10^3 \times 450\)

= 20.25 J

Q. 2: Determine how much heat energy is lost if 50 Kg water is cooled from 600\degreeC to 200\degreeC. Specific heat of water is given as \(C = 4.2 \times10^3 JKg^-1° C.\)

Solution:

Given values are,

Mass of water, m = 50 Kg,

Specific heat of water, C = \(4.2 \times10^3 JKg^-1°\)

Temperature difference,

\(\Delta T = – 40°\)

Heat energy by formula is,

Q = \(mc\Delta T \)

Q = \(50 \times 4.2 \times 10^3 × (-400 ) \)

Q= – 840 J

Share with friends

Customize your course in 30 seconds

Which class are you in?
5th
6th
7th
8th
9th
10th
11th
12th
Get ready for all-new Live Classes!
Now learn Live with India's best teachers. Join courses with the best schedule and enjoy fun and interactive classes.
tutor
tutor
Ashhar Firdausi
IIT Roorkee
Biology
tutor
tutor
Dr. Nazma Shaik
VTU
Chemistry
tutor
tutor
Gaurav Tiwari
APJAKTU
Physics
Get Started

Leave a Reply

avatar
  Subscribe  
Notify of

Get Question Papers of Last 10 Years

Which class are you in?
No thanks.