A train traveling at 42 kilometers per hour, passes through a tunnel in 5 minutes. A second train, twice as long as the first one, traveling at the same speed, takes 6 minutes to pass through the tunnel. What is the length of the second train?
a: 1600
b:1400
c:1200
d:1350
Answers
Answer:
b. 1400 m
Hope this helps.
Step-by-step explanation:
Let a be the length of the tunnel and let b be the length of the first train.
To completely pass through the tunnel, the distance travelled by the first train is a+b.... "a" gets the front of the train from entrance to exit, and then an additional "b" to get the rest of the train out.
The distance travelled by the second train is a+2b since it is two times longer.
--- Train 1 ---
speed = 42 km / hr
time = 5 min = 1/12 hr
distance = speed × time
=> a + b = 42 / 12 = 7 / 2 = 3.5 km ... (1)
--- Train 2 ---
speed = 42 km / hr
time = 6 min = 1/10 hr
distance = speed × time
=> a + 2b = 42 / 10 = 4.2 km ... (2)
Subtracting equation (1) from equation (2) gives
b = 4.2 - 3.5 = 0.7 km
The second train's length is
2b = 2 × 0.7 km = 1.4 km = 1400 m
Answer:b) 1400
Step-by-step explanation:self explanatory