Speed, Time and Distance
- Two donkeys are standing 400 metres apart. First donkey can run at a speed of 3 m/sec and the second can run at 2 m/sec. If two donkeys run towards each other after how much time (in seconds) will they bump into each other?
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Distance between both donkeys = 400 metre.
Relative speed = (3 + 2) m./sec. = 5 m./sec.∴ Required time = Distance Relative speed = 400 = 80 seconds 5 Correct Option: B
Distance between both donkeys = 400 metre.
Relative speed = (3 + 2) m./sec. = 5 m./sec.∴ Required time = Distance Relative speed = 400 = 80 seconds 5
- A man travels for 14 hours 40 minutes. He covers half of the journey by train at the rate of 60 km/hr and rest half by road at the rate of 50 km/hr. The distance travelled by him is :
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Let total distance covered be 2x km.
Total time = 14 hours 40 minutes= 14 40 hours = 14 2 hours 60 3 = 44 hours 3 Time = Distance Speed
According to the question,x + x = 44 60 50 3 ∴ 5x + 6x = 44 300 3 ⇒ 11x = 44 300 3 ⇒ x = 44 × 300 = 400 3 11
∴ Total distance
= 2x = 2 × 400 = 800 kmCorrect Option: B
Let total distance covered be 2x km.
Total time = 14 hours 40 minutes= 14 40 hours = 14 2 hours 60 3 = 44 hours 3 Time = Distance Speed
According to the question,x + x = 44 60 50 3 ∴ 5x + 6x = 44 300 3 ⇒ 11x = 44 300 3 ⇒ x = 44 × 300 = 400 3 11
∴ Total distance
= 2x = 2 × 400 = 800 km
- Sound travels 330 metre in a second.When the sound follows the flash of lightning after 10 seconds the thunder cloud will be at a distance of :
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Distance = Speed × Time
= 330 × 10 = 3300 metreCorrect Option: D
Distance = Speed × Time
= 330 × 10 = 3300 metre
- A man travelled a distance of 61 km. in 9 hours, partly by walking at the speed of 4 km./hr. and partly on bicycle at the speed of 9 km./hr. The distance covered by walking is
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Let the distance covered on foot be x km.
∴ Distance covered on cycle = (61 – x) km.Time = Distance Speed ∴ x + 61 − x = 9 4 9 ⇒ x − x = 9 − 61 4 9 9 ⇒ 9x − 4x = 81 − 61 36 9 ⇒ 5x = 20 36 9 ⇒ x = 20 × 36 = 16 km. 9 5 Correct Option: A
Let the distance covered on foot be x km.
∴ Distance covered on cycle = (61 – x) km.Time = Distance Speed ∴ x + 61 − x = 9 4 9 ⇒ x − x = 9 − 61 4 9 9 ⇒ 9x − 4x = 81 − 61 36 9 ⇒ 5x = 20 36 9 ⇒ x = 20 × 36 = 16 km. 9 5
- A farmer travelled a distance of 61 km in 9 hours. He travelled partly on foot at a speed of 4 km/hour and partly on bicycle at a speed of 9 km/hour. The distance travelled on foot is :
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Length of journey on foot = x km. (let).
∴ Length of journey on cycle = (61 – x ) km.
According to the question,Time = Distance Speed ∴ x + 61 − x = 9 4 9 ⇒ 9x + 244 − 4x = 9 36
⇒ 5x + 244 = 36 × 9 = 324
⇒ 5x = 324 – 244 = 80⇒ x = 80 = 16 km 5 Correct Option: B
Length of journey on foot = x km. (let).
∴ Length of journey on cycle = (61 – x ) km.
According to the question,Time = Distance Speed ∴ x + 61 − x = 9 4 9 ⇒ 9x + 244 − 4x = 9 36
⇒ 5x + 244 = 36 × 9 = 324
⇒ 5x = 324 – 244 = 80⇒ x = 80 = 16 km 5