1. Relativistic Mass and Momentum
SPH4U

2. Rest Mass
The rest mass of an object is its inertial mass:

3. Relativistic Mass
However, the mass of an object as defined by: will be larger if the object is moving with respect to a given frame of reference since the object will also have kinetic energy.

4. Relativistic Energy
Einstein suggested that the relativistic energy of an object may be given by:

5. Relativistic Mass
The relativistic mass is therefore:

6. Kinetic Energy
And the kinetic energy of the object is:

7. Example
An electron moves at 0.860c in a laboratory. Calculate the electron’s (a) rest energy, (b) total energy, and (c) kinetic energy in electron volts.

8. Example
An electron moves at 0.860c in a laboratory. Calculate the electron’s (a) rest energy, (b) total energy, and (c) kinetic energy in electron volts. (a)

9. Example
An electron moves at 0.860c in a laboratory. Calculate the electron’s (a) rest energy, (b) total energy, and (c) kinetic energy in electron volts. (a)

10. Example
An electron moves at 0.860c in a laboratory. Calculate the electron’s (a) rest energy, (b) total energy, and (c) kinetic energy in electron volts. (a)

11. Example
An electron moves at 0.860c in a laboratory. Calculate the electron’s (a) rest energy, (b) total energy, and (c) kinetic energy in electron volts. (b)

12. Example
An electron moves at 0.860c in a laboratory. Calculate the electron’s (a) rest energy, (b) total energy, and (c) kinetic energy in electron volts. (b)

13. Example
An electron moves at 0.860c in a laboratory. Calculate the electron’s (a) rest energy, (b) total energy, and (c) kinetic energy in electron volts. (c)

14. Relativistic Momentum
The momentum of an object is also relativistic:

15. Minutephysics
Another way of looking at relativistic energy and momentum:

16. More Practice Textbook questions p. 583 #1, 3, 4 p. 578 #10, 11
“Paradoxes in Special Relativity Assignment”