Date post: | 13-Dec-2015 |
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Ff and FP are equal in magnitude, mg and FN are also equal in magnitude. The net force on the book is zero, so it is in equilibrium.
The bat is applying a force FB and gravity is pulling downward mg. The forces are NOT balanced so the ball is NOT in equilibrium. It is accelerating.
Since the box is not moving, it is not accelerating. The net force on the box must be zero, so these three forces must balance each other. The box is in equilibrium.
Even though the box is moving, it is not accelerating because the speed is constant. The box is in equilibrium, so the free body diagram is the same as in the previous question.
6. What is the minimum number of forces (besides zero) that can be applied to an object in equilibrium?
8. A ball is falling through the air at a constant speed of 35 m/s. If the weight of the ball is 5 Newtons, what is the force of air resistance on the ball?
5 Newtons. Since the object is falling at a constant velocity, it is not accelerating. The forces must be balanced, so air resistance must equal gravity.
9. Dalyn is pushing upfield with a force of 200 N. If a linebacker hits him from the left with a force of 150 N, what is the net force on Dalyn?
10. With what force would Charles have to hit Dalyn to hold Dalyn at a constant velocity in question 9?(Better grammar!)
Constant velocity means all the forces must be balanced. Charles must apply an equal force in the opposite direction (this is called an equilibrant force), 250 N, 37° left of back downfield.