A lump of lead with mass 0.5kg is dropped from height of 20m onto a hard surface it doesn't rebound but remains there at rest for a long period of time. A, find change in heat , change in work, change in internal energy for the lead during this process?
A lump of lead with mass 0.5kg is dropped from
height of 20m onto a hard surface it doesn't
rebound but remains there at rest for a long
period of time. A, find change in heat , change
in work,
Students
98.1
To find the change in heat, change in work, and change in internal energy for the lead during this process, we need to consider the various forms of energy involved.
1. Change in heat (Q):
Since the lump of lead does not bounce back or rebound, all of its initial potential energy is converted into other forms of energy upon impact with the hard surface. In this case, the potential energy is converted mainly into heat due to the deformation of the lead and the surface. Hence, the change in heat (Q) is equal to the initial potential energy of the lead.
The initial potential energy (U) of the lead is given by the formula:
U = m * g * h
where
m = mass of the lead (0.5 kg),
g = acceleration due to gravity (9.8 m/s²),
h = height (20 m).
Therefore,
U = 0.5 kg * 9.8 m/s² * 20 m = 98 J (joules).
Hence, the change in heat (Q) is 98 J.
2. Change in work (W):
The lump of lead does not rebound, so no work is done by or on the lead during this process. Work is defined as the product of the force exerted on an object and the displacement of the object in the direction of the force. Since the lead remains at rest, there is no displacement and therefore no work done.
Hence, the change in work (W) is zero.
3. Change in internal energy (ΔU):
The change in internal energy (ΔU) can be found using the conservation of energy principle. In this case, as the lead impacts the hard surface, all of its initial potential energy is converted into other forms of energy, mainly heat. Therefore, the change in internal energy (ΔU) is equal to the change in heat (Q).
ΔU = Q
ΔU = 98 J
Hence, the change in internal energy (ΔU) is 98 J.
In summary:
Change in heat (Q) = 98 J
Change in work (W) = 0 J
Change in internal energy (ΔU) = 98 J