1. susan pushes her dad, david, on an ice rink with a force of 30 n. she weighs 45 kg and her dad weighs 100 kg. what are the accelerations of susan and david?

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.

it is b. absorbs thermal energy

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.