Calculate Train Speed Increase: 84 km/h in 495.7s | Force Physics Problem

[mandy9008]

Homework Statement

A freight train has a mass of 1.4x10⁷ kg. If the locomotive can exert a constant pull of 6.7x10⁵ N, how long does it take to increase the speed of the train from rest to 84 km/h?

Homework Equations

F=ma
a=v/t

The Attempt at a Solution

I converted 84 km/h into 23.3 m/s.
F=ma
6.7x10^5 N=1.4x10^7 m (a)
a= .047 m/s^2

a=v/t
.047 m/s^2=(23.3 m/s)/t
t=495.7s --> 2.97x10^4 min

 

[rock.freak667]

That looks correct.

 

[mandy9008]

when I enter it it says that it differs significantly from the correct answer

 

[rock.freak667]

when I enter it it says that it differs significantly from the correct answer

the t =2.97x10⁴ min is not correct.

t= 495.7 s should be correct.

 

[mandy9008]

the question asks for time in minutes

 

[mandy9008]

i converted it and got 8.26 min and got it correct.i don't know what i was thinking converting it before haha thanks