Question

A 100 m long train is moving with a uniform velocity of 45 km/hr. Calculate the time taken by the train to cross a bridge of length 1 km.

Answer 1

There are two different lengths that are covered by the train bridge length and its own length. A body is said to have uniform velocity if it covers equal distance in equal intervals of time in a particular direction, however, the time intervals may be small.

Complete step by step solution: Length to covered by train = bridge length + its own length
d=1000m+100m=1100m
train speed = 45 km/hr =$45 \times {\text{ }}\dfrac{{1000}}{{3600}} = 12.5m/s$
so, time taken = distance/velocity=$\dfrac{{1100}}{{12.5}} = 88$s

Additional information: Velocity is defined as the rate change of displacement per unit time. Speed in a specific direction is also known as velocity. Velocity is equal to displacement divided by time. There is a major difference between velocity and speed like, Speed, being a scalar quantity, is the rate at which an object covers distance. The average speed is the distance (a scalar quantity) per time ratio.On the other hand, velocity is a vector quantity; it is direction-aware. Velocity is the rate at which the position changes.

Note: In this type of questions always find out the total distance cover by the object and use the distance by velocity. It helps to find the time taken by the object. We should assume that both the trains run into its uniform velocity. A body is said to have uniform velocity if it covers equal distance in equal intervals of time in a particular direction, however, the time intervals may be small.