Answer:
Part 1.: Work done by the force is 3461 J
Part 2: Work done by the force of friction is 972.8 J
Explanation:
part 1.
Since the displacement is horizontal, the only component of the 88.2 N force applied on the block is the horizontal component (which carries the cos(26.9) (the cosine of the angle with the horizontal). Then the component of the force acting on the 44 m displacement is: 88.2 * cos(26.9) . Then the work done by this component can be found by multiplying this quantity times the displacement (44 m), which gives:
88.2 * cos (26.9) * 44 = 3460.8878 J
which we can round to the nearest whole number as: 3461 J
Part 2.
The force of kinetic friction is the product of the normal force exerted by the surface on the block, times the coefficient of kinetic friction. Now the surface reacts with the normal force opposing the net vertical force applied by the block on the surface. Notice that in this case, the normal force doesn't just oppose the weight (m * g) of the object, since there is a vertical component of the external 88.2 N force ( the one that uses the sin(26.9) ) that is acting opposite to the gravitational force. This pointing upwards force component is going to subtract from the weight, thus making the normal force smaller than what it would be if just the object's weight was acting vertically. In magnitude, this is the normal force calculation:
Normal = Weight - 88.2 * sin(26.9)
Normal = [17.5 * 9.8 - 88.2 * sin(26.9) ] N
Normal = 131.6 N
At this point, we can calculate the value of the force of kinetic friction (product between the normal force and the coefficient of kinetic friction):
Kinetic friction force: 0.168 * 131.6 N = 22.1088 N
Now the product of this force times the displacement will give us the magnitude of the work done by the force of friction:
22.1088 N * 44 m = 972.7872 J
that we can round to 972.8 J
It is important to notice that the work done by the force of friction is negative due to the fact that the force acts opposite to the displacement of the block.
