Question

A PARTICLE MOVING IN A STRAIGHT LINE COVERS HALF OF TOTAL DISTANCE WITH SPEED OF 3 M/S THE OTHER HALF OF DISTANCE IS COVERED IN 2 EQUAL TIME INTERVALS WITH SPEED OF 4.5 M/S AND 7.5 M/S . AVERAGE SPEED OF PARTICLE DURING THIS MOTION IS.

Answer 1

Td1= First half distance
Td2=Second half distance

Td1 = 3m/s

Td2(1) = 4.5m/s
Td2(2) = 7.5m/s

Td2 Average = (4.5+7.5)/2=6m/s

Total average =(3+6)/2= 4.5 m/s

Answer 2

<----------------------4--------------------->

A------------------B------------C-------------D

<----2------------> <-----1----> <-----1---->

LET TOTAL DISTANCE=4

FROM A-B

SPEED=3M/S

TIME=2/3

FROM B-C

SPEED=4.5M/S

TIME=1/4.5

FROM C-D

SPEED=7.5 M/S

TIME=1/7.5

AVERAGE SPEED=TOTAL DISTANCE COVERED /TOTAL TIME TAKEN

                              =4 /    2/3+1/4.5+1/7.5

                               =4/   46/45

                              =3.9m/s