Ou are pushing a 20-kg box along a horizontal floor. Friction acts on the box. When you apply a horizontal force of magnitude 48 N, the box moves at a constant velocity. What is the magnitude of the frictional force on the box?

The magnitude of the frictional force is 48.02 N

Explanation:

Mass of box = 20 kg

Weight of the box (Normal reaction) = mass × acceleration due to gravity = 20 ×9.8 = 196 N

Horizontal force applied = 48 N

Coefficient of friction = horizontal force ÷ normal reaction = 48 ÷ 196 = 0.245

Frictional force = coefficient of friction × normal reaction = 0.245 × 196 N = 48.02 N

(75°f − 32) × 5/9 = 23.889°c

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.