Question

plzz answer 10 i ii and iii in the following image

Answer 1

slope gives acceleration
SO
!)AB:y/x=30/4=7.5m/s^-2
BC: constant,straight line 0
CD downwards:30/2= -15m/s^-2
2)
area under vt graph gives displacement
AB:1/2*30*4=60m
BC:4*30=120m
CD:1/2*2*30=60m

3)TOTAL Displacement =Total Area
60+120+30=210m

Answer 2

Concept :- acceleration is the rate of change of velocity .
if we solve graphical method , then
acceleration is slope of V - t graph

now ,
(1)★ acceleration in part AB = slope of part AB = ( velocity at B - velocity at A)/( time at B - time at A )

= ( 30 - 0)/( 4 - 0) = 30/4 = 7.5 m/s²


★acceleration in part BC = ( velocity at C - velocity at B )/( time at C - time at B)

= ( 30 - 30)/( 8 -4) = 0 m/s²

★ acceleration in part CD = ( velocity at D - velocity at C )/( time at D - time at C )

= ( 0 - 30)/( 10 - 8) = -30/2 = -15m/s²


concept :- displacement in V-t graph is area enclosed by graph .

now ,
★displacement in part AB = area of ∆ = 1/2× height × base = 1/2 × 30 × 4 = 60 m

★ displacement in part BC = area of rectangle = length × breath = 30 × 4 = 120 m

★ displacement in part CD = area of ∆
= 1/2 × 30 × 2= 30 m

(3) total displacement = displacement in part AB + displacement in part BC + displacement in part CD

=( 60 + 120 + 30 ) m = 210 m