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 $a$ to find $a \approx 0.16 \, \mathrm{m/s^2}$.

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 $42 \mathrm {~m} / \mathrm { s }$