Answer:
3.At equilibrium, its instantaneous velocity is at maximum
Explanation:
The motion of a mass on the end of a spring is a simple harmonic motion. In a simple harmonic motion, the total mechanical energy of the system is constant, and it is sum of the elastic potential energy (U) and the kinetic energy of the mass (K):
where
k is the spring constant
x is the displacement of the spring from equilibrium
m is the mass
v is the speed
As we see from the formula, since the total energy E is constant, when the displacement (x) increases, the speed (v) increases, and viceversa. Therefore, when the mass is at its equilibrium position (which corresponds to x=0), the velocity of the mass will be maximum.
Answer:
The change in internal energy for the system = - 78.87 KJ = - 79 KJ to 2 s.f
Explanation:
The first law of thermodynamics states that energy can neither be created nor destroyed but can only be transformed from one form to another.
It goes further to explain that change in the internal energy of a system (ΔU) is the sum of heat exchanged (Q) and the work done (W) by the system or on the system.
If work is done by the system, sign of work is ‘-’, if work is done on the system, the sign of work is ‘+’.
If heat is released by the system, the sign of q is ‘-’. And if heat is gained by the system, then the sign of q is ‘+’.
ΔU = Q + W
Q = 130 J
W = - 79 KJ = - 79000 J
ΔU = 130 - 79000 = - 78870 J = - 78.87 KJ = - 79 KJ
<span>the state of matter of the medium i think
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Answer:
13.7 J
Explanation:
In absence of air resistance, the mechanical energy of the object is conserved during the fall: this means that the initial gravitational potential energy that it has at the beginning of the fall will be entirely converted into kinetic energy when the book is just about the hit the ground.
Therefore, this also means that we can calculate the mechanical energy at the beginning of the fall, as this will be equal to the mechanical energy just before the book hits the ground.
At the beginning of the fall, the mechanical energy is all gravitational potential energy:
where
m = 0.5 kg is the mass of the book
is the acceleration of gravity
h = 2.8 m is the height above the ground
Substituting,
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