mechanics Help.... plz some1 help me solve tis... and also how is itz graph gonna be??

Question

. A particle starts with velocity 30m/s& has constant deceleration of 10m/s^2.
find velocity after 1 sec, (b) time when velocity=0
(c) time taken to reach velocity of -30m/s.

i want to get the answer solving the graph not using equation..

Answer 1

v(t)=30-10*t

at t=1
v(1)=20
when v(t)=0
t=3

when v(t)=-30
t=6

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