b. A body is moving with a velocity of 12m/s and it comes to rest after covering 18m. What is the acceleration and time taken to come to rest?
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b. A body is moving with a velocity of 12m/s and it comes to rest after covering 18m. What is the acceleration and time taken to come to rest?
please don't copy from net
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Acceleration = Velocity x distance
=12x18
=216 m/s ²
Time=velocity x distance
=12x18
=216 seconds
Verified answer
Answer:
acceleration = -4m/s^2 , time = 3s
Explanation:
v^2 = u^2 + 2aS
0 = (12)^2 + 2(a)(18)
0 = 144+36a
0 = 4 + a
a = -4
S = ut + 1/2(a)(t)^2
18 = 12t + 1/2(-4)(t^2)
18 = 12t - 2t^2
2t^2 - 12t + 18 = 0
t^2 - 6t + 9 =
t^2 - 3t - 3t + 9 = 0
t(t-3)-3(t-3) = 0
(t-3)(t-3) = 0
(t-3) = 0 (zero product rule)
t = 3s