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## Homework Statement

An object with a mass of 2kg gets accelerated from 15m/s to 25m/s.

A: What is the work done in effecting this velocity change?

B: The distance moved was 8m, what force produced the acceleration?

C: How long did it take to produce the acceleration (presumed uniform)?

## Homework Equations

Equations of Motion

## The Attempt at a Solution

Part A:

[tex]

W=\frac{1}{2}m(v^2 - u^2) \\

W=\frac{1}{2}2(25^2 - 15^2) \\

W= 25^2 - 15^2 = 400J

[/tex]

Part B:

[tex]

v^2=u^2+2as \\

∴ a = \frac{v^2 - u^2}{2s} \\

F=ma \\

F=2 \times \frac{25^2 - 15^2}{2 \times 8} \\

F=2 \times \frac{400}{16} \\

F=2 \times 25 = 50N

[/tex]

Part C

[tex]

v=u+at \\

∴ t = \frac{v-u}{a} \\

t= \frac{25-15}{25} = 0.4s

[/tex]

My biggest problem is the values, they just dont seem right to me, 0.4s to accelerate a 2kg mass from 15 to 25m/s using 50N over 8m?

Any help appreciated :).