Question

a car moving on a straight path at 16 m/s undergoes uniform retardation to come to rest in a distance of 0.4m.the retardation time is ?​

Answer 1

Given:

• initial velocity = u = 16m/s
• final velocity = v = 0 m/s (come to rest)
• distance = s = 0.4 m

Solution :

since car undergoes uniform retardation we can use equations of motion;

3rd equation of Motion:

• v² = u² + 2as
• 0² = 16² + 2(-a)(0.4)
• 0 = 256 - 0.8a
• -256 = - 0.8a
• a = 256 / 0.8
• a = 320 m/s²

1st equation of Motion:

• v = u + at
• 0 = 16 + (-320)t
• -16 = -320t
• t = 16/320
• t = 1/20
• t = 0.05 s

★ Retardation time to come to rest is 0.05s.

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