A motorist is travelling at 90 kmph, when he observes a traffic signal 250 m ahead of him turns red. The traffic signal is timed to stay red for 12 secs.

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written 8.4 years ago by

teamques10 ★ 68k

• modified 4.5 years ago

If the motorist wishes to pass the signal without stopping just as it turns green, Determine i) The required uniform deceleration of motor ii) The speed of motor as it passes the signal

engineering mechanics

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written 8.4 years ago by

teamques10 ★ 68k

Given: $u=90$ kmph $=25 m/s $

$$t=12 sec \space\space\space S=250 m $$

Applying, $S= ut+(1/2)at2 \\ 250= 25(12) + 0.5(a)(144) \\ a= - 0.694 m/s2 $

Now, applying $v = u +at \\ v = 25+(-0.694)(12) = 16.67 m/s $

Uniform deceleration of motor is $- 0.694 m/s2$ & the speed of motor as it passes the signal is $16.67 m/s$

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