Answer please class 9 physics
Answers
Answer:
Average speed = Total Distance / Total Time
S1 = 50 km/hr T1 = 0.5 hr
D1 = S1 x T1 = 50 x 0.5 = 25 km
S2 = 30 km/hr T2 = 0.26 hr
D2 = S2 x T2 = 30 x 0.26 = 7.8 km
S3 = 70 km/hr T3 = 0.76 hr
D3 = S3 x T3 = 70 x 0.76 = 53.2 km
Total Distance = D1 + D2 + D3 = 25 + 7.8 + 53.2
Total Distance = 86 km
Total Time = T1 + T2 + T3 = 0.5 + 0.26 + 0.76
Total Time = 1.52 hr
Average Speed = 86/1.52
Average Speed = 56.58 km/hr
Answer:
The average speed of the car is roughly 54.29 km/hr.
Explanation:
Given:
- Speed of the train for the first 30 minutes (0.5 hours) = 50 km/hr
- Speed of the train for the next 15 minutes (0.25 hours) = 40 km/hr
- Speed of the train for the next 60 minutes (1 hour) = 60 km/hr
To find:
The average speed of the car
Method to find:
First, we need to find the total distance covered by the train.
Distance = Speed * Time
Let the distance covered in the 3 time periods be d₁, d₂ and d₃.
d₁ = 50 km/hr * 0.5 hrs
⇒ d₁ = 25 km
d₂ = 40 km/hr * 0.25 hrs
⇒ d₂ = 10 km
d₃ = 60 km/hr * 1 hr
⇒ d₃ = 60 km
Total Distance Covered = d₁ + d₂ + d₃
⇒ Total Distance Covered = (25 + 10 + 60) km
⇒ Total Distance Covered = 95 km
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Now, we need to find the total time taken.
Total Time Taken = (0.5 + 0.25 + 1) hrs
⇒ Total Time Taken = 1.75 hrs
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With the above information, we can now find the average speed.
Average Speed = Total Distance / Total Time
⇒ Average Speed = 95 km / 1.75 hr
⇒ Average Speed = 54.2857142857 km/hr ≈ 54.29 km/hr
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Hope it helps!