1. A train is running at a speed of 40 km/hr and it crosses a post in 18 seconds. What is the length of the train?
| |
A. 190 metres
|
B. 160 metres
|
C. 200 metres
|
D. 120 metres
|
Answer : Option C
Explanation :
Speed of the train, v = 40 km/hr = 40000/3600 m/s = 400/36 m/s
Time taken to cross, t = 18 s
Distance Covered, d = vt = (400/36)× 18 = 200 m
Distance covered is equal to the length of the train = 200 m
Time taken to cross, t = 18 s
Distance Covered, d = vt = (400/36)× 18 = 200 m
Distance covered is equal to the length of the train = 200 m
2. A train ,130 meters long travels at a speed of 45 km/hr crosses a bridge in 30 seconds. The length of the bridge is
| |
A. 270 m
|
B. 245 m
|
C. 235 m
|
D. 220 m
|
Answer : Option B
Explanation :
Assume the length of the bridge = x meter
Total distance covered = 130+x meter
total time taken = 30s
speed = Total distance covered /total time taken = (130+x)/30 m/s
=> 45 × (10/36) = (130+x)/30
=> 45 × 10 × 30 /36 = 130+x
=> 45 × 10 × 10 / 12 = 130+x
=> 15 × 10 × 10 / 4 = 130+x
=> 15 × 25 = 130+x = 375
=> x = 375-130 =245
Total distance covered = 130+x meter
total time taken = 30s
speed = Total distance covered /total time taken = (130+x)/30 m/s
=> 45 × (10/36) = (130+x)/30
=> 45 × 10 × 30 /36 = 130+x
=> 45 × 10 × 10 / 12 = 130+x
=> 15 × 10 × 10 / 4 = 130+x
=> 15 × 25 = 130+x = 375
=> x = 375-130 =245
3. A train has a length of 150 meters . it is passing a man who is moving at 2 km/hr in the same direction of the train, in 3 seconds. Find out the speed of the train.
| |
A. 182 km/hr
|
B. 180 km/hr
|
C. 152 km/hr
|
D. 169 km/hr
|
Answer : Option A
Explanation :
Length of the train, l = 150m
Speed of the man , Vm= 2 km/hr
Relative speed, Vr = total distance/time = (150/3) m/s = (150/3) × (18/5) = 180 km/hr
Relative Speed = Speed of train, Vt - Speed of man (As both are moving in the same direction)
=> 180 = Vt - 2
=> Vt = 180 + 2 = 182 km/hr
Speed of the man , Vm= 2 km/hr
Relative speed, Vr = total distance/time = (150/3) m/s = (150/3) × (18/5) = 180 km/hr
Relative Speed = Speed of train, Vt - Speed of man (As both are moving in the same direction)
=> 180 = Vt - 2
=> Vt = 180 + 2 = 182 km/hr
4. A train having a length of 240 m passes a post in 24 seconds. How long will it take to pass a platform having a length of 650 m?
| |
A. 120 sec
|
B. 99 s
|
C. 89 s
|
D. 80 s
|
Answer : Option C
Explanation :
v = 240/24 (where v is the speed of the train) = 10 m/s
t = (240+650)/10 = 89 seconds
t = (240+650)/10 = 89 seconds
5. A train 360 m long runs with a speed of 45 km/hr. What time will it take to pass a platform of 140 m long?
| |
A. 38 sec
|
B. 35 s
|
C. 44 sec
|
D. 40 s
|
Answer : Option D
Explanation :
Speed = 45 km/hr = 45×(10/36) m/s
= 150/12 = 50/4 = 25/2 m/s
Total distance = length of the train + length of the platform
= 360 + 140 = 500 meter
Time taken to cross the platform = 500/(25/2) = 500×2/25 = 40 seconds
= 150/12 = 50/4 = 25/2 m/s
Total distance = length of the train + length of the platform
= 360 + 140 = 500 meter
Time taken to cross the platform = 500/(25/2) = 500×2/25 = 40 seconds
No comments:
Post a Comment