Question

A train accelerates from its metropolitan cruising speed of 22 m/s to its countryside cruising speed of 32 m/s. If it takes the train 142 seconds to do this, what is its acceleration?

10 m/s2
14.2 m/s2
4.4 m/s2
0.07 m/s2

Answer 1

Since it mentions in the problem that it took 142 seconds for 22 m/s to become 32 m/s, one should multiply 142 by the answer choices. This will determine how many m/s2 was needed to get the change in speed. Then it will be added to the 22m/s to see what is closest to 32 m/s.

142*10 = 1420+22 = 1442. Too much.
142*14.2 = 2016.4+22 = 2038.4. Too much. Even rounding doesn't do it justice, of course.
142*4.4 = 624.8+22 = 646.8. Too much. Rounding won't work here, either.
142*0.07 = 9.94+22 = 31.94. This is the closest out of all of them, and when rounded it comes up as 32.

So, the answer would be 0.07 m/s2.

Answer 2

Acceleration of the train is 0.07 m/s²

Step-by-step explanation:

Initial speed of the train, u = 22 m/s

Final speed of the train, v = 32 m/s

Time taken by the train to do the process is 142 seconds

We have to find the acceleration of the train. It is given by the rate of change of speed of the train i.e.

`a=(v-u)/(t)`

`a=(32\ m/s-22\ m/s)/(142\ s)`

`a=0.07\ m/s^2`

So, the acceleration of the car is 0.07 m/s². Hence, the correct option is (d) 0.07 m/s²