Exercise 2: Suppose that a force of 20.4N acts through and parallel to a displac

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?

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?

Explanation / Answer

given,

force = 20.4 N

displacement = 135.2 m

mass = 5.8 kg

initial velocity = 0 m/s

force = mass * accleration

20.4 = 5.8 * acceleration

acceleration = 3.517 m/s^2

v^2 = u^2 + 2as

v^2 = 0 + 2 * 3.517 * 135.2

final speed v = 30.838 m/s

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