There is no frictional force between the hand and the book, but there is a frictional force exerted upward on the book by the wall. What happens to this frictional force if the hand pushes horizontally twice

Two resistors r1 and r2 may be connected either in series or parallel across an ideal battery with emf ε. we desire the rate of energy dissipation of the parallel combination to be 8.75 times that of the series combination. if r1 = 105 ω, what are the (a) smaller and (b) larger of the two values of r2 that result in that dissipation rate?

Two balls, each with a mass of 0.5 kg, collide on a pool table. is the law of conservation of momentum satisfied in the collision? explain why or why not

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