5.3 Mass and Energy

Select all that apply based on E = mc².

• Energy and mass can be converted into one another based on the speed of light.

• Energy and mass can be converted into one another based on the length of a triangle's hypotenuse.

• Energy is conserved individually.

• Mass is conserved individually.

• Energy and mass are conserved together.

Select all that apply to relativistic energy.

• an object at rest will have an energy of mc².

• an object in motion will have an energy of mc²

• as an object's speed approaches the speed of light, it will have an energy of mc²

• as an object's speed approaches the speed of light, it will obtain an infinite amount of energy

Select all that apply. Which are examples of an object gaining mass?

• Adding more almonds into a jar.

• Heating up a jar.

• Taking almonds from a jar.

• Cooling down a jar.

• Moving a jar of almonds around.

Why don't we notice relativistic mass or energy changes in everyday life?

• Einstein was just joking.

• The changes are too small for us to notice in everyday life.

• We're not paying close enough attention.

• The changes are too large for us to notice in everyday life.

A 4.7 kg object is at rest. How much energy does it have?

• 0 J

• 4.7 J

• 1.4 * 10⁹ J

• 4.2 * 10¹⁷ J

A 4.7 kg object is travelling at a speed of 0.49c. How much energy does it have?

• 0 J

• 4.9 * 10¹⁷ J

• 1.6 * 10¹⁷ J

• 4.9 * 10⁹ J

Select all that apply. What are some challenges in converting mass into energy?

• Our current level of technology doesn't allow us to convert much mass into energy.

• We don't have enough mass to convert into energy.

• The conversion of mass to energy can create radioactive byproducts that are harmful to us and the environment.

• With the amount of energy released from mass-energy conversion, we need safety protocols in place to protect ourselves from large explosions.

• We have too much mass to convert into energy.