How often do you rely on media for scientific information to make decisions in your life? (No weather answer please)
2 answers:
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Hi there!
(a)
Recall that:
W = Work (J)
F = Force (N)
d = Displacement (m)
Since this is a dot product, we only use the component of force that is IN the direction of the displacement. We can use the horizontal component of the given force to solve for the work.
To the nearest multiple of ten:
(b)
The object is not being displaced vertically. Since the displacement (horizontal) is perpendicular to the force of gravity (vertical), cos(90°) = 0, and there is NO work done by gravity.
Thus:
(c)
Similarly, the normal force is perpendicular to the displacement, so:
(d)
Recall that the force of kinetic friction is given by:
Since the force of friction resists the applied force (assigned the positive direction), the work due to friction is NEGATIVE because energy is being LOST. Thus:
In multiples of ten:
(e)
Simply add up the above values of work to find the net work.
Nearest multiple of ten:
(f)
Similarly, we can use a summation of forces in the HORIZONTAL direction. (cosine of the applied force)
Nearest multiple of ten:
Answer:
The driver hits the stationery dog because the applied force is less than required force
Explanation:
Kinetic energy will be given by
where m is the mass of the vehicle and v is the speed/velocity of the vehicle.
Substituting 800 Kg for m and 20 m/s for v we obtain
Frictional force by vehicle pads is given by
where d is the distance moved
Substituting 160000 for KE and 50 m for d we obtain
Therefore, the vehicle hits the dog since the required force is 3200N but the driver applied only 2000 N