Exercise 2: Suppose that a force of 20.4N acts through and parallel to a displac
ID: 1603524 • Letter: E
Question
Exercise 2: Suppose that a force of 20.4N acts through and parallel to a displacement of 135.2m on some object with mass 5.8kg. If the only effect was to increase its speed from an initial value of zero, how fast would it now be going? 30.838 m/s
Exercise 3: Referring to Exercise 2, suppose that the velocity of the object was initially not zero and that this velocity was not changed by the force. Clearly there would be at least one other force involved as the acceleration was zero. An example of this would have the 20.4N force acting horizontally on a box that slides at a steady speed across the floor. How much work was done by the force?
since the box is steadily sliding
accelaration a = 0 m/s^2
the opposite force to 20.4 N should be = 20.4 N
Work done by the net force = 20.4*135.2 = 2758 J
**My question**
In Exercise 3, they tell you that now, the object moves at constant velocity, and there are 2 forces acting on the object. The net work on the object must be 0, since its energy is not changing. Is the work done by the 20.4 N force in this new situation the same as in Exercise 2? Yes or no??
Explanation / Answer
Work done by the net force = 20.4*135.2 = 2758 J
When the object moves at constant velocity,
the work done by the 20.4 N force in this new situation shoud be -2758 J
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