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JAMB Physics 2016 Paper

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Question : 23

Total: 48

A train with an initial velocity of 20ms^-1 is subjected to a uniform deceleration of 2ms^-2. The time required to bring the train to a complete halt is

40s
10s
20s
5s

Solution:

Concept:

Use the first equation of motion to find the time taken for the train to stop under uniform deceleration.

Explanation:

Initial velocity,

u = 20 \, \mathrm{ms^{-1}}

Final velocity,

v = 0 \, \mathrm{ms^{-1}}

(train comes to a halt)

Deceleration,

a = -2 \, \mathrm{ms^{-2}}

(negative because it opposes motion)

Using

v = u + at

:

0 = 20 + (-2)t

2t = 20

t = 10 \, \mathrm{s}

Answer:

The time required is

10 \, \mathrm{s}

, which is option B.

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