Answer:
The right solution is "61.557 MJ". A further explanation is given below.
Explanation:
The given values are:
Force,
F = 306 N
Drive,
D = 125 miles,
i.e.,
= 201168
meters
As we know,
The work done will be:
=
On substituting the given values, we get
=
=
On converting it in "MJ", we get
=
=
Complete question:
A fireman of mass 80 kg slides down a pole. When he reaches the bottom, 4.2 m below his starting point, his speed is 2.2 m/s. By how much has thermal energy increased during his slide?
Answer:
The thermal energy increased by 3,099.2 J
Explanation:
Given;
mass of the fireman, m = 80 kg
initial position of the fireman, hi = 4.2 m
final speed, v = 2.2 m/s
The change in the thermal energy is calculated as;
ΔE + (K.Ef - K.Ei) + (Uf - Ui) = 0
where;
ΔE is the change in the thermal energy
K.Ef is the final kinetic energy
K.Ei is the initial kinetic energy
Uf is the final potential energy
Ui is the initial potential energy