The efficiency of an ideal Carnot heat engine can be written as:
where
is the temperature of the cold region
is the temperature of the hot region
For the engine in our problem, we have
and
, so the efficiency is
Answer:
B) Gets smaller
Explanation:
The difference of phase between current and voltage in a AC circuit is the phase angle and it depends on the value of Z ( circuit impedance)
Z = R + X where R is the resistive component and X the reactance component, which is due either to a presence of an inductor or a capacitor. In any case the total impedance depends on R the resistive, and the phase angle φ is:
tan⁻¹ φ = X/R
Have a look to a pure capactive circuit (we are talking about AC current) in this case current leads voltage by 90⁰. If we add a resistor in the circuit the current still will lead a voltage but in this condition the phase angle will be smaller,
If R increase, X/R decrease and tan⁻¹ φ also decrease
Assuming constant acceleration, the goalie slows the ball from 18 m/s to rest in 0.035 s, so that the acceleration felt by the ball is
power = (voltage) x (current)
17 w = (5 v) x (current)
current = (17 w) / (5 v) = 3.4 Amperes
