The change in the kinetic energy refers to the work done in displacing a body, thus, the change in the kinetic energy of an object refers to the work done on the object.
The correct formula to use is:
W = Initial kinetic energy - Final kinetic energy;
Where, W = change in kinetic energy
Final kinetic energy and initial kinetic energy = 1/2 MV^2
Initial velocity = 15 m/s
Final velocity = 13.5 m/s
Initial mass = 0.650 kg
Final mass = 0.950 kg
W = 1/2 [0.650* (15 *15)] - 1/2 [0.950 * (13.5 * 13.5)]
W = 146.25 - 173.13 = 26.88
Therefore, the change in kinetic energy is 26.88 J.
The negative sign has to be ignored, because change in kinetic energy can not be negative.
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For this case, the first thing we must do is define a reference system.
Suppose that the positive direction of the reference system is upward.
We have that the sum of forces in the vertical axis is given by:
Fy = Fp - Fg
Substituting values:
Fy = 5500 - 6000
Fy = - 500
The negative sign means that the direction of the force with respect to the defined coordinate system is downward.
Answer:
The net force is:
↓ 500N
<u>Mechanics</u> is the branch of physics which deals with the study of motion of material objects.
<u><em>Divisions</em></u>
There are three major division of mechanics
Statics
Kinematics
Dynamics.
