Study the speed time graph of a body shown in Figure. and answer the following questions:
(a) What type of motion is represented by `OA` ?
(b) What type of motion is represented by `AB` ?
( c ) What type of motion is represented by `BC` ?
(d) Find out acceleration of the body.
(e) Find out retardation of the body .
(f) Find out the distance travelled by the body from `A` to `B`

Answer

`(a) uniformly accelerated , (b) uniform velocity , ( c ) uniformly retarded , (d) `1.5 m//s^(2)` , (e) `36 m`

Explanation

(a) As speed - time graph `OA` is a straight line with a positive slope , the motion is uniformly accelerated motion.
(b) As `AB` is parallel to time axis , its slope is zero . Therefore , acceleration of the body is zero . The body is moving with a uniform velocity.
( c ) As speed - time graph `BC` is a straight line with negative slope, the motion is uniformly decelerated motion ,
(d) From `O` to `A` ,
change in speed `= 6 - 0 = 6 m//s`
time taken `= 4 - 0 = 4 s`
Thus , acceleration `= ("change in speed")/("time taken") = (6 m//s) /( 4 s) = 1.5 m//s^(2)`
(e) From `B` to `C`
change in speed `= 0 - 6 = - 6 m//s`
time taken `= 16 - 10 = 6 s`
Thus , acceleration `= ("change in speed")/("time taken") = ( - 6 m//s)/( 6 s) = - 1 m//s^(2)`
Negative sign indicates retardation.
(f) From `A` to `B` , the velocity is uniform.
`:.` distance travelled ` = "velocity" xx "time" = 6 xx ( 10 - 4) = 36 m`