Answer:
The efficiency of a Stirling engine is 74%
Explanation:
Given:
Temperature of gas when it is cold
K
Temperature of gas when it is hot
K
The efficiency of a stirling engine,




∴ 
Therefore, the efficiency of a Stirling engine is 74%
Answer:
3.97 m/s
Explanation:
Speed is defined as the distance covered per unit time. Therefore, s=d÷t=d/t
Where d is distance and t is time
Given distance of 5 km and time of 21 minutes the speed would be given by dividing 5 km by 21 min. However, speed is expressed as km/h or m/s or miles per hour etc. So we nees to get our speed in one of these standard units.
Going for m/s
Conversion
1 km has 1000m hence
5 km=5*1000=5000m
1 min has 60 seconds hence
21 min=21*60=1260 s
Speed=5000m÷1260s=3.9682539682538 m/s
Rounded off, s=3.97 m/s
I’m not sure sorry I really wish I could help
As we know that frequency and wavelength are dependent on each other
and this is given by

here we know that
= wavelength
f = frequency
c = speed of wave
while for energy and intensity of wave we know that
Energy = 
here A = amplitude of wave
so energy directly depends on amplitude of wave
so correct answer will be
<em>A) Energy</em>