A train starts from rest and accelerates uniformly until it has traveled 5.6 km and acquired a forward velocity of $42 \mathrm {~m} / \mathrm { s }$ The train then moves at a constant velocity of $42 \mathrm {~m} / \mathrm { s }$ for 420 s.The train then slows down uniformly at $$0.065 \mathrm {~m} / \mathrm { s } ^ { 2 }$$ until it is brought to a halt.The acceleration during the first 5.6 km of travel is closest to which of the following?
A)0.16 m/ $\mathrm { s }^2$
B)0.14 m/ $\mathrm { s }^2$
C)0.17 m/ $\mathrm { s }^2$
D)0.19 m/ $\mathrm { s }^2$
E)0.20 m/ $\mathrm { s }^2$

Question

Quizplus · Accepted Answer

Using the equation $v^2 = u^2 + 2as$, where $v = 42 \, \mathrm{m/s}$, $u = 0$, and $s = 5600 \, \mathrm{m}$, we solve for $a$: $a = \frac{v^2}{2s} = \frac{42^2}{2 \times 5600} \approx 0.16 \, \mathrm{m/s^2}$.

A Train Starts from Rest and Accelerates Uniformly Until It 42 m/s42 \mathrm {~m} / \mathrm { s }42 m/s

A Train Starts from Rest and Accelerates Uniformly Until It $42 \mathrm {~m} / \mathrm { s }$