Question

A train is moving with uniform velocity on a
straight track. A boy moving at 4 km/h due
east observes that the train is moving due
north. Another boy moving at 1 km/h due
south claims that the train is moving
towards north-east. What is the speed of the
train in ground frame?​

Answer 1

Answer:

Relative Velocity:

Let us consider two objects

A

and

B

, which have velocities

v

A

and

→

v

B

respectively. Let the velocity of a third object

C

be

→

v

C

.

Then the relative velocity of the object

C

with respect to the object

A

can be given as:

→

v

C

A

=

→

v

C

−

→

v

A

.

The relative velocity of the object

C

with respect to the object

B

can be given as:

→

v

C

B

=

→

v

C

−

→

v

B

.