Answer:
42 km/h was the average speed of the car for its three-hour trip.
Explanation:
Diameter of the car wheel = d = 0.4 m
Radius of the car wheel = r = 0.5 d = 0.5 × 0.4 m =0.2 m
Distance covered in 1 complete revolution = 
Distance covered in 100,000 complete revolution,D = 

1 m = 0.001 km
125,663.71 m = 125,663.71 × 0.001 km = 125.66371 km
Time taken to complete 100,000 revolution by a wheel = t = 3 hours
Speed of car : S

42 km/h was the average speed of the car for its three-hour trip.
Answer:
c) those caused by parasites
The wise and careful use of energy is called CONSERVATION
D) waves are used to transmit the rail signal though the air. these waves are encoded at different frequencies for different stations