Question

the images below show four pairs of magnets. the magnets in different pairs do not affect each other. all the magnets shown are made of the same material, but some of them are different sizes. think about the magnetic force between the magnets in each pair. select the pair with the magnetic force of smallest magnitude. pair 1 pair 2 pair 3 pair 4 submit work it out

Explanation:

Step1: Analyze the factors affecting magnetic force

The magnetic force between magnets depends on the size of the magnets (larger magnets have stronger magnetic fields) and the distance between them.

Step2: Compare Pair 1 and Pair 3

Pair 1 has a larger magnet on the left compared to Pair 3. Since the distance is the same (44.4 mm), Pair 3 has weaker magnetic force (smaller magnet on the left).

Step3: Compare Pair 2 and Pair 4

Pair 2 has a larger magnet on the left compared to Pair 4. Pair 4 has two smaller magnets. But Pair 3 has a smaller magnet on the left than Pair 4 (Pair 3 left - small, Pair 4 left - same size as Pair 4 right which is small but Pair 3 left is part of a pair with larger distance? No, wait re - evaluate.
Wait, actually, magnetic force \(F\propto\frac{m_1m_2}{r^2}\) (where \(m_1\) and \(m_2\) are magnetic'masses' (related to size, for same material, larger size means larger \(m\)) and \(r\) is the distance).
Pair 3: two small magnets (small \(m_1\) and \(m_2\)) and distance \(r = 44.4\)mm.
Pair 1: one large (\(m_1\) large) and one small (\(m_2\) small) magnet, \(r = 44.4\)mm. Since \(m_1\) (Pair1 left) > \(m_1\) (Pair3 left), \(F_{Pair1}>F_{Pair3}\).
Pair 2: one large (\(m_1\) large) and one small (\(m_2\) small) magnet, \(r = 29.6\)mm. Since \(r_{Pair2}F_{Pair1}\) (because \(F\propto\frac{1}{r^2}\)).
Pair 4: two small magnets (\(m_1\) and \(m_2\) small) and \(r = 29.6\)mm. Since \(r_{Pair4}F_{Pair3}\)

Answer:

Pair 3