A code of ethics for psychologists helps to do all of the following except __________.
2 answers:
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Answer:
a) 1.89 m/s b) 172.1 N
Explanation:
a)
- Applying the work-energy theorem, if we can neglect the friction between truck and road, the total change in kinetic energy must be equal to the work done by the external forces.
- This work, is just 4,475 J.
- So we can write the following equation:
- where m= mass of the truck = 2.5*10³ kg.
- So, we can find the speed v, as follows:
b)
- The work done by the man, is just the horizontal force applied, times the displacement produced by the force horizontally:
- We can solve for F, as follows:
Initial height: 66.5 m
Explanation:
The problem can be solved by using the principle of conservation of energy.
If we neglect air resistance, the total mechanical energy of the car is conserved during the fall, therefore we can write:
where :
is the kinetic energy of the car at the top (it starts from rest)
is the gravitational potential energy of the car at the top, with:
m = the mass of the car
g = the acceleration of gravity
h = the heigth of the car
is the kinetic energy of the car just before hitting the ground, with
v = 130 km/h final speed of the car
is the gravitational potential energy of the car at the bottom
Re-arranging the equation, we find
and we have:
Solving for h, we find the initial height of the car:
Learn more about kinetic energy and potential energy:
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