7 Work, Energy & Power

Which of the following best describes work in physics?

• Energy transferred by force over a distance

• Energy stored in an object at rest

• Force acting without displacement

• The ability to store energy

Calculate the kinetic energy of a 2 kg object moving at 3 m/s.

• 3 J

• 6 J

• 9 J

• 12 J

What is the SI unit of work?

• Newton

• Joule

• Watt

• Horsepower

Which form of energy is associated with the motion of an object?

• Potential Energy

• Thermal Energy

• Kinetic Energy

• Elastic Energy

Clarify the term 'elastic potential energy'.

• Energy due to height

• Energy due to motion

• Energy stored in stretched or compressed materials

• Energy from chemical reactions

Which statement best explains the first law of thermodynamics?

• Energy cannot be created or destroyed, only transformed

• Heat can only flow from hot to cold

• Energy stored in springs is potential

• Efficiency is always 100%

Distinguish between conduction and convection.

• Conduction is heat transfer through liquids only, convection is through solids

• Conduction is direct contact heat transfer, convection is heat transfer through fluids

• Conduction is always faster

• Conduction requires motion, convection does not

Potential energy depends on:

• Mass and height

• Mass and speed

• Temperature

• Force and displacement

Conservation of mechanical energy applies when:

• Heat is added to a system

• Work is done on the system

• No energy is lost to heat or friction

• Energy is destroyed

Which of the following is NOT a mode of heat transfer?

• Conduction

• Compression

• Convection

• Radiation