A weight lifter manages to lift a 147 kg weight a distance of 1.1 m. Treat her as a thermodynamic system and find how much heat (in kcal) she must put out if her internal energy decreases by 3620 J during the lift.
Not sure how to answer this.
To answer this question, we need to understand the relationship between work, heat, and internal energy in thermodynamics.
According to the first law of thermodynamics, the change in internal energy (ΔU) of a system is equal to the heat (Q) added to the system minus the work (W) done by the system:
ΔU = Q - W
In this case, the weight lifter is performing work by lifting the weight. The work done is given by the formula:
W = F * d
where F is the force applied and d is the distance over which the force is applied.
The force can be calculated using the formula:
F = m * g
where m is the mass of the weight and g is the acceleration due to gravity.
Substituting the values given in the question, we have:
m = 147 kg
g = 9.8 m/s^2
d = 1.1 m
Using the formula for force, we can find the work done:
W = F * d = (m * g) * d
Now we can calculate the work done by the weight lifter.
Next, we know that the internal energy decreases by 3620 J. This means that ΔU = -3620 J.
Substituting these values into the first law of thermodynamics equation, we have:
-3620 J = Q - W
Now, we can solve for Q, which is the amount of heat that the weight lifter must put out during the lift.
To convert the final answer from Joules to kilocalories (kcal), we need to use the conversion factor:
1 kcal = 4184 J
So, the final answer will be in kcal.