A neon sign _________ light. A. emits B. filters C. reflects D. transmits
1 answer:
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We can use the law of conservation of energy to solve the problem.
The total mechanical energy of the system at any moment of the motion is:
where U is the potential energy and K the kinetic energy.
At the beginning of the motion, the ball starts from the ground so its altitude is h=0 and therefore its potential energy U is zero. So, the mechanical energy is just kinetic energy:
When the ball reaches the maximum altitude of its flight, it starts to go down again, so its speed at that moment is zero: v=0. So, its kinetic energy at the top is zero. So the total mechanical energy is just potential energy:
But the mechanical energy must be conserved, Ef=Ei, so we have
and so, the potential energy at the top of the flight is
The total mechanical energy of the system at any moment of the motion is:
where U is the potential energy and K the kinetic energy.
At the beginning of the motion, the ball starts from the ground so its altitude is h=0 and therefore its potential energy U is zero. So, the mechanical energy is just kinetic energy:
When the ball reaches the maximum altitude of its flight, it starts to go down again, so its speed at that moment is zero: v=0. So, its kinetic energy at the top is zero. So the total mechanical energy is just potential energy:
But the mechanical energy must be conserved, Ef=Ei, so we have
and so, the potential energy at the top of the flight is
The third equation of free fall can be applied to determine the acceleration. So that Paola's acceleration during the flight is 39.80 m/.
Acceleration is a quantity that has a direct relationship with velocity and also inversely proportional to the time taken. It is a vector quantity.
To determine Paola's acceleration, the third equation of free fall is appropriate.
i.e =
± 2as
where: V is the final velocity, U is the initial velocity, a is the acceleration, and s is the distance covered.
From the given question, s = 20.1 cm (0.201 m), U = 4.0 m/s, V = 0.
So that since Poala flies against gravity, then we have:
=
- 2as
0 = - 2(a x 0.201)
= 16 - 0.402a
0.402a = 16
a =
= 39.801
a = 39.80 m/
Therefore Paola's acceleration is 39.80 m/.