Question

A 20.0kg box rests on a table. A 10.0kg box is placed on top of the 20.0kg box. Determine the normal force that the table exerts in the 20.0kg box and the normal force that the 20.0kg box exerts on the 10kg box.

Answer 1

1) Weight is the force of gravity, which is equal to mass times the acceleration due to gravity, which is 9.8 m/s^2. So the weight of the box is 20*(-9.8) = -196 N, and that is also the normal force acting on the box.

2)The normal force acting on the 20-kg box is equal to the total weight of the two boxes (which have a total mass of 30 kg), because the table feels the weight of both boxes but is only contacting the 20-kg box. The normal force that the 20-kg box exerts on the 10-kg box is equal to the weight of the 10-kg box (upwards)

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