Force of kinesin molecule within cells

[omc1]

Homework Statement

Within cells, small organelles containing newly synthesized proteins are transported along microtubules by tiny molecular motors called kinesins. What force does a kinesin molecule need to deliver in order to accelerate an organelle having mass 0.028 pg from rest to 2.8 microm/s over a time of 45.0 micros?

Homework Equations

ft=mv

The Attempt at a Solution

i converted the micro to m and s, 2.8x10^-6 m/s and 2.8x10^-17 kg and 4.5x10^-5 s. for my answer i got 1.87x10^-18m/s but its wrong...thanks for help!

 

[nasu]

The conversions look OK. I suppose you made a mistake in your calculations.