Gravitation: common misconceptions

If your child says… “Equal areas mean equal speeds.”

Ask together

With a shorter Sun–planet distance, would equal travel sweep the same area?

What’s true

In a noncircular planetary orbit, equal swept areas require faster motion nearer the Sun.

If your child says… “Opposite pulls cannot turn anything.”

Ask together

Do these arrows turn the rod in opposite directions or the same direction?

What’s true

Opposite forces along different lines can turn objects.

If your child says… “I add both pulls, even when they point opposite ways.”

Ask together

What remains when the two arrows at P are equal and opposite?

What’s true

Equal gravitational pulls in opposite directions cancel, including paired contributions inside a uniform spherical shell.

If your child says… “Deeper means stronger gravity.”

Ask together

Does the graph rise towards the centre?

What’s true

Inside a uniform sphere, outer layers cancel and enclosed mass decreases inward.

If your child says… “Gravitational potential must be positive.”

Ask together

If the tabletop is zero, is potential energy below it positive or negative?

What’s true

With zero at infinity, gravitational potential near an isolated mass is negative.

If your child says… “Heavier objects need a faster escape launch.”

Ask together

After cancelling the object’s mass, where could its heaviness change the answer?

What’s true

At the same launch point, object mass changes both energies equally, leaving escape speed unchanged.

If your child says… “Adding energy always increases speed.”

Ask together

Does less kinetic energy mean faster motion?

What’s true

Between circular orbits, potential energy rises while kinetic energy falls.

If your child says… “Astronauts float because gravity has gone.”

Ask together

If gravity vanished, what would keep the spacecraft’s path curving?

What’s true

A hollow spacecraft does not block external gravity, and floating does not show gravity is absent.