Two bar magnets are held with their north poles facing. A student pushes them from 6 cm apart to 2 cm apart and holds them there. What happens to the energy stored in the system?

Two magnets with like poles facing are squeezed to 1 cm apart, then released. They spring apart to 9 cm and stop. How did the energy stored in the magnet system change as they flew apart?

Two balloons rubbed on hair both carry negative charge and hang 30 cm apart. A boy pushes them until they hang 10 cm apart. What happens to the energy stored between the balloons?

Two carts carry magnets with south poles facing and are clamped 3 cm apart. A teacher slides the clamps until the carts are 12 cm apart. How has the stored energy changed?

Two repelling magnets are pushed from 8 cm to 3 cm apart and clamped there. A student claims the system now stores more energy. Which observation is evidence for that claim?

Two ring magnets on a rod repel, so the top one floats 5 cm above the lower one. A student sets a mass on the top ring and the gap closes to 2 cm. Where did the extra energy stored between the magnets come from?

Two magnets with north poles facing are moved from 5 cm apart to 1 cm apart by a machine. The system stores more energy at 1 cm than it did at 5 cm.

A steel paper clip is stuck to a magnet. A girl pulls the clip off and holds it 5 cm away. How has the energy stored in the magnet-and-clip system changed?

A magnet's north pole is held 4 cm from another magnet's south pole, then released. The magnets snap together. What happened to the energy stored in the system?

An engine burn raises a probe from a 400 km orbit to a 1200 km orbit above Earth. Earth and the probe attract each other. What happens to the stored energy of the Earth-probe system?

A negatively charged balloon clings to a wall that has become positively charged where it touches. A girl peels the balloon 20 cm off the wall. What happens to the energy stored between balloon and wall?

Two pairs of magnets are each clamped 2 cm apart. One pair has like poles facing, and the other has opposite poles facing. Both pairs are released. What happens to the energy stored in each pair?

A librarian lifts a 3 kg book from a table onto a shelf 1.5 m higher and lets go. The book rests there, not moving. What became of the energy the librarian transferred?

A boy squeezes two repelling magnets together, then releases them and they shoot apart across the bench. Where did the energy that moved the magnets come from?

Two books rest on the same high shelf. One book has twice the mass of the other. Which book's system with Earth stores more energy?

A girl pulls a paper clip off a magnet and drops it. The clip flies back and sticks with a click. Which sequence describes the energy in the magnet-and-clip system?

A crane lowers a 200 kg steel beam slowly from 12 m to 3 m above the ground, and the beam is not moving at either height. What happened to the stored energy of the Earth-and-beam system?

Four identical pairs of magnets are each held with their south poles facing each other, at separations of 1 cm, 3 cm, 5 cm and 8 cm. Which pair stores the most energy?

Four identical paper clips are held by threads at 1 cm, 2 cm, 4 cm and 7 cm from identical magnets that attract them. Which clip-and-magnet pair stores the most energy?

Four identical 2 kg balls rest on shelves 0.5 m, 1.0 m, 2.0 m and 3.0 m above the same floor. Which ball's system with Earth stores the least energy?