- #1

anthonywsadler

- 2

- 1

Using work...

Work = K.E.

F * D = K.E.

m*a*D = K.E. = 10 kg * 10 m/s/s * 10 m = 1000 Joules

However, using kinematics...

x = vo*t + at^2

10 m = 0 m/s + 10 m/s/s * t^2

10 m/10 m/s/s = t^2

t = 1 sec (the time it takes the box to go 10 meters)

vf = vo*t + a*t

vf = a*t = 10 m/s/s * 1 s = 10 m/s

KE = 1/2*m*v^2 = 1/2*10kg*(10 m/s)^2 = 500 Joules

Where is this factor of 2 difference coming from? Is the issue coming from how the problem is written? Thank you for your help!