Physics · Kinematics · Video solution

A bus travels at 30 km/h for the first 2 h of a journey and then travels at 50 km/h for the…

Question

A bus travels at 30 km/h for the first 2 h of a journey and then travels at 50 km/h for the next 2 h of the journey. Find the ratio of the speeds to the distances traveled at the two speeds.

Answer

The ratio of speeds is 3:5 and the ratio of distances is 3:5.

Concept: Speed, distance, time ratio

Step-by-step solution

  1. 1. Given Data

    First part: speed S₁ = 30 km/h, time T₁ = 2 h.

    S1=30 km/h,T1=2 hS_1 = 30 \text{ km/h}, T_1 = 2 \text{ h}
  2. 2. Given Data

    Second part: speed S₂ = 50 km/h, time T₂ = 2 h.

    S2=50 km/h,T2=2 hS_2 = 50 \text{ km/h}, T_2 = 2 \text{ h}
  3. 3. Distance Formula

    Distance is calculated as speed multiplied by time.

    D=S×TD = S \times T
  4. 4. Calculate Distances

    Distance for first part D₁ = S₁ × T₁ = 30 km/h × 2 h = 60 km.

    D1=30×2=60 kmD_1 = 30 \times 2 = 60 \text{ km}
  5. 5. Calculate Distances

    Distance for second part D₂ = S₂ × T₂ = 50 km/h × 2 h = 100 km.

    D2=50×2=100 kmD_2 = 50 \times 2 = 100 \text{ km}
  6. 6. Ratio of Speeds

    Ratio of speeds S₁ : S₂ = 30 : 50 = 3 : 5.

    S1:S2=30:50=3:5S_1 : S_2 = 30 : 50 = 3 : 5
  7. 7. Ratio of Distances

    Ratio of distances D₁ : D₂ = 60 : 100 = 3 : 5.

    D1:D2=60:100=3:5D_1 : D_2 = 60 : 100 = 3 : 5
  8. 8. Final Answer

    The ratio of speeds is 3:5 and the ratio of distances is 3:5.

    S1:S2=3:5,D1:D2=3:5S_1:S_2 = 3:5, D_1:D_2 = 3:5
  9. 9. Yaad rakho / Key takeaway

    When time is constant, distance is directly proportional to speed.

Remember

When time is constant, distance is directly proportional to speed.

Common mistake

Confusing direct and inverse proportionality in ratios.

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