Two students, Alice and Bob, try to move identical heavy backpacks, A and B. Alice exerts a force to pull backpack A horizontally along the floor. The backpack does not move because its strap is caught under a heavy desk. Bob lifts backpack B vertically from the floor onto a desk. Which student does the most work on their backpack, and which backpack gains the most energy?
533 exam-style questions on CIE IGCSE Physics 1.7 Energy, work and power, covering 1.7.1a Energy stores and energy transfers, 1.7.1b Conservation of energy, 1.7.1c Kinetic and gravitational potential energy, 1.7.2 Work done, 1.7.3 Energy resources, 1.7.3a Energy resources and electricity generation, 1.7.3b Nuclear fusion as an energy source, 1.7.3c Efficiency of energy transfer, and 1.7.4 Power. Each one has a worked solution and a mark scheme showing where the marks go.