Home
Class 12
PHYSICS
A train goes through a 1100 m long tunne...

A train goes through a `1100 m` long tunnel at a constant speed of `72 km//h`. The last compartment comes out one minute after the entry of engine in the tunnel. Find the length of train (including engine).

A

`80 m`

B

`100 m`

C

`1200m`

D

`1000m`

Text Solution

Verified by Experts

The correct Answer is:
B
`t=60 sec`
Total distance travelled `=1100+L`
Speed `=72 (km)//(hr)=20 m//sec`
`rArr60=(1100+L)/(20)rArr1200=1100+L`
`rArrL=100 m`
Promotional Banner

Topper's Solved these Questions

Similar Questions

Explore conceptually related problems

A train runs along an unbanked circular track of radius 30 m at a speed of 54 km/h. The mass of the train is 10^(6) kg. What provides the centripetal force required for this purpose - The engine or the rails ? What is the angle of banking required to prevent wearing out of the rail ?

A train of length l is moving with a constant speed v circular track of radius R, the engine of the train emits a whistle of frequency f_(0) . Find the frequency heard by a guard at the rear end of the train.

Represent the following situations in the form of quadratic eqautions : (1) The area of a rectangular plot is 528 m^(2) . The length of the plot (in metres) is one more than twice its breadth. We need to find the length and breadth of the plot. (2) The product of two consecutive positive integers is 306. We need to find the integers. (3) Rohan's mother is 26 years older than him. The product of their ages (in years) 3 years from now will be 360. We would like to find Rohan's present age. (4) A train travels a distance of 480 km at a uniform speed. If the speed had been 8km/h less, it would have taken 3 hours more to cover the same distance. We need to find the speed of the train.

Two trains A and B of length 400 m each are moving on two parallel tracks with a uniform speed of 72 km h^(-1) in the same direction, with A ahead of B. The driver of B decides to overtake A and accelerates by 1 m s^(-2) . If after 50 s, the guard of B just brushes past the driver of A, what was the original distance between them ?

Two trains A and B of length 400 m each are moving on two parallel tracks with a uniform speed of 72 km h^(-1) in the same direction, with A ahead of B. The dirver of B decides to overtake A and accelerates by 1 ms^(-2) . If after 50s, the guard of B just brushed past the driver of A, what was the original distance between them ?

Thin films, including soap bubbles and oil show patterns of alternative dark and bright regions resulting from interference among the reflected light waves. If two waves are in phase, their crests and troughs will coincide. The interference will be constructive and the amplitude of resultant wave will be greater then either of constituent waves. If the two wave are not of phase by half a wavelength (180^(@)) , the crests of one wave will coincide width the troughs of the other wave. The interference will be destructive and the amplitude of the resultant wave will be less than that of either constiuent wave. 1. When incident light I, reaches the surface at point a, some of the light is reflected as ray R_(a) and some is refracted following the path ab to the back of the film. 2. At point b, some of the light is refracted out of the film and part is reflected back through the film along path bc. At point c, some of the light is reflected back into the film and part is reflected out of the film as ray R_(c) . R_(a) and R_(c) are parallel. However, R_(c) has traveled the extra distance within the film of abc. If the angle of incidence is small, then abc is approximately twice the film's thickness . If R_(a) and R_(c) are in phase, they will undergo constructive interference and the region ac will be bright. If R_(a) and R_(c) are out of phase, they will undergo destructive interference and the region ac will be dark. I. Refraction at an interface never changes the phase of the wave. II. For reflection at the interfere between two media 1 and 2, if n_(1) gt n_(2) , the reflected wave will change phase. If n_(1) lt n_(2) , the reflected wave will not undergo a phase change. For reference, n_(air) = 1.00 . III. If the waves are in phase after reflection at all intensities, then the effects of path length in the film are: Constrictive interference occurs when 2 t = m lambda // n, m = 0, 1,2,3 ,... Destructive interference occurs when 2 t = (m + (1)/(2)) (lambda)/(n) , m = 0, 1, 2, 3 ,... If the waves are 180^(@) out of the phase after reflection at all interference, then the effects of path length in the film area: Constructive interference occurs when 2 t = (m + (1)/(2)) (lambda)/(n), m = 0, 1, 2, 3 ,... Destructive interference occurs when 2 t = (m lambda)/(n) , m = 0, 1, 2, 3 ,... 72. A film with index of refraction 1.50 coats a glass lens with index of refraction 1.80. What is the minimum thickness of the thin film that will strongly reflect light with wavelength 600 nm?

Two trains one of length l_(1)=630m and other of length l_(2)=120m move uniformly in two parallel paths in opposite direction with speed mu_(1)=48 km//h and mu_(2)=102 km//h respectively.