- #1
FaraDazed
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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 don't seem right to me, 0.4s to accelerate a 2kg mass from 15 to 25m/s using 50N over 8m?
Any help appreciated :).