A large unknown mass is subjected to the variable force as shown above. If the mass starts at rest (t = 0), and is moving at 60 m/s (t = 40 s), determine the mass of the object.

Which of the following best describes internal energy? a. the difference between the kinetic and potential energies of the particles in a system b. the sum of the kinetic and potential energies of the particles in a system c. the sum of the kinetic and thermal energies of the particles in a system d. the difference between the kinetic and thermal energies of the particles in a system