A bag weighing 20 N is pushed horizontally a distance of 35 m across a
1 answer:
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Answer:
<h2>1) there is no work done on the system</h2><h2>2) A) Using a lever to lift 100 newtons up to 4 meters on to a shelf</h2><h2 /><h2>3) P = 140 W</h2><h2>4) D) In a closed system, a system that isolated from its surrounds, the total energy of the system is conserved</h2>Explanation:
1) As we know that work done is the product of force and the displacement of the point of action where force is applied
So here we have
as there is no displacement in the direction where the force is applied
2)As we know that work is product of force and displacement
So we will have
So maximum work is done on
A) Using a lever to lift 100 newtons up to 4 meters on to a shelf
3)
As we know that power is rate of work done
so we have
4)
As per energy conservation we know that
D) In a closed system, a system that isolated from its surrounds, the total energy of the system is conserved
Answer:
C. It speeds up, and the angle increases
Explanation:
We can answer by using the Snell's law:
where
are the refractive index of the first and second medium
is the angle of incidence (measured between the incident ray and the normal to the surface)
is the angle of refraction (measured between the refracted ray and the normal to the surface)
In this problem, light moves into a medium that has lower index of refraction, so
We can rewrite Snell's law as
and since
this means that
which implies
so, the angle increases.
Also, the speed of light in a medium is given by
where c is the speed of light and v the refractive index: we see that the speed is inversely proportional to n, therefore the lower the index of refraction, the higher the speed. So, in this problem, the light will speed up, since it moves into a medium with lower index of refraction.