Question
You're approaching an intersection at $50 \mathrm{~km} / \mathrm{h}(13.9 \mathrm{~m} / \mathrm{s})$ You see the light turn yellow when you're $35 \mathrm{~m}$ from the intersection. Assume a reaction time of 0.6 s before braking begins and a braking acceleration of $-3.0 \mathrm{~m} / \mathrm{s}^{2}$. (a) Will you be able to stop before the intersection? (b) The yellow light stays on for $3.4 \mathrm{~s}$ before turning red. If you continue at $50 \mathrm{~km} / \mathrm{h}$ without braking, will you make it through the $9.5-\mathrm{m}$ -wide intersection before the light turns red?
Step 1
This can be done using the formula $s_1 = v_0 \cdot t_1$, where $v_0$ is the initial speed and $t_1$ is the reaction time. Substituting the given values, we get $s_1 = 13.9 \, \text{m/s} \cdot 0.6 \, \text{s} = 8.34 \, \text{m}$. Show more…
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