The correct answer is:
Work is negative, the environment did work on the object, and the energy of the system decreases.
In fact, the work-energy theorem states that the work done by the system is equal to its variation of kinetic energy:

In this problem, the variation of kinetic energy
is negative (because the final velocity is less than the initial velocity), so the work is negative, and this means that the environment did work on the object, and its energy decreased.
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Answer:
741 J/kg°C
Explanation:
Given that
Initial temperature of glass, T(g) = 72° C
Specific heat capacity of glass, c(g) = 840 J/kg°C
Temperature of liquid, T(l)= 40° C
Final temperature, T(2) = 57° C
Specific heat capacity of the liquid, c(l) = ?
Using the relation
Heat gained by the liquid = Heat lost by the glass
m(l).C(l).ΔT(l) = m(g).C(g).ΔT(g)
Since their mass are the same, then
C(l)ΔT(l) = C(g)ΔT(g)
C(l) = C(g)ΔT(g) / ΔT(l)
C(l) = 840 * (72 - 57) / (57 - 40)
C(l) = 12600 / 17
C(l) = 741 J/kg°C
Answer:
a = 0.1067 [m/s²]
Explanation:
In order to solve this problem, we must first draw a free body diagram with the forces acting on it.
a)
In the attached image we can find the free body diagram.
b)
The net force can be found by performing a sum of forces on the X-axis, these forces are seen in the free body diagram.
∑Fx = Fr
where:
Fr = resultant force [N] (units of Newtons)
![F_{r}=275+275-310\\F_{r}=240[N]](https://tex.z-dn.net/?f=F_%7Br%7D%3D275%2B275-310%5C%5CF_%7Br%7D%3D240%5BN%5D)
c)
Acceleration can be found by means of Newton's second law, which tells us that the sum of the forces in a body or the resulting force is equal to the product of mass by acceleration.
∑F = m*a
where:
m = mass = 2250 [kg]
a = acceleration [m/s²]
![240=2250*a\\a=0.1067[m/s^{2} ]](https://tex.z-dn.net/?f=240%3D2250%2Aa%5C%5Ca%3D0.1067%5Bm%2Fs%5E%7B2%7D%20%5D)