Question

A train moves a distance of 10 M with a constant speed of 40 m per second and Moves the next 5 M with a constant speed of 30 M per second calculate its average speed

Answer 1

Let this frame of reference be moving with a speed of 10 m/s .

Now lets calculate new velocities of train and parrot.

The velocity of train will be zero since the frame of reference and train, both are moving with same velocity.

The velocity of parrot will be v=10+5=15 m/s. (As the frame of reference and parrot are moving in opposite direction , we will add both the velocities) .

Now the problem has been converted to one body problem

A parrot with velocity 15 m/s has to cover a distance of 150 m. Calculate the time required.

Using

s=vts=vt

t=s/vt=s/v

t=150/15t=150/15

t=10sect=10sec

So 10 seconds is the time required by the parrot to cover a distance of 150 m of a moving train with a velocity of 10 m/s