Question

A piece of rope is pulled by two people in a tug-of-war. Each pulls with 400 N of force. What is the tension in the rope? A. zero B. 400 N C. 200 N D. 800 N E. none of these 18. A book sits motionless on a table indicating that A. The weight of the book and the normal force on it form a Newton's Third Law pair. B. The book is in dynamic equilibrium. C. There are no forces acting on the book since the table cancels gravity. D. All of the above. E. None of the above.

Answer 1

The tension in the rope is D. 800 N.

Step-by-step explanation:

In a tug of war, two forces are acting in opposite directions. In this case, each person is pulling with 400 N of force. So the total force acting on the rope is 800 N in the direction of the stronger force. That means the tension in the rope is also 800 N.

The correct option for the book sitting motionless on a table is B. The book is in dynamic equilibrium.

Step-by-step explanation:

The fact that the book is sitting motionless on a table means that the forces acting on it are balanced. Two forces are acting on the book: gravity pulling it downwards and the normal force from the table pushing it upwards. Since the book is not moving, that means these two forces are equal in magnitude and opposite in direction. This is an example of static equilibrium. However, since the book is not accelerating, it is also an example of dynamic equilibrium.