Answer
given,
high temperature reservoir (T_c)= 464 K
efficiency of reservoir (ε)= 25 %
temperature to decrease = ?
increase in efficiency = 42 %
now, using equation




T_C = 348 K
now,
if the efficiency is equal to 42$ = 0.42



Answer:
d) The stone will have about 50 joules of kinetic energy and 0 joules of potential energy .
Explanation:
Given :
Initial Potential energy ,
.
Initial Kinetic energy ,
. ( because ball is in rest )
Now , we know , kinetic energy is maximum when an object reaches ground .
Also , potential energy is zero when an object is in ground .
We know , by conservation of energy :
Initial total energy = Final total energy

Therefore , option d) is correct .
Average v = (initial v + final v)/2
= (14 m/s + 0 m/s)/2
= 7 m/s
Your average velocity during braking is 7 m/s