Lesson: Relativistic Mass Physics • 9th Grade

In this lesson, we will learn how to calculate the increase in the mass of an object as it moves at greater speeds relative to an observer.

Lesson Plan

Students will be able to

understand that an object has a greater mass the faster it is moving in the reference frame of the observer,
use in all permutations.

Lesson Worksheet

Q1:

Person A is sitting on a train that is moving at 80 km/h. Person B is standing next to the train tracks. The following formula can be used to calculate how much extra mass person A appears to have, as perceived by person B: .

If person A has a rest mass, , of 80 kg, how much extra mass are they perceived to have by person B? Knowing that the extra mass will have a nonzero value, answer in scientific notation to two decimal places.

Q2:

The graph shows relativistic mass, , against rest mass, , for objects moving at speed relative to an observer. What is the value of ? Give your answer as a multiple of .

Q3:

What is the mass, as measured by an observer, of a metal sphere that has a rest mass of 2.00 kg and is moving at relative to the observer? Give your answer to two decimal places.