D. Unbalanced forces are acting on it.
hope this helped
-- There's a force of 240N pushing her backwards.
-- She's maintaining a steady speed (of 2.5 m/s) .
-- In order to maintain a steady speed (no acceleration),
the forces on her must be balanced. So she's maintaining
a steady force of 240N forward.
-- Every time she moves 1 m forward, she does work of
(force) x (distance) = 240 joules.
-- She moves 2.5 meters forward every second.
So she's doing (240 x 2.5) = 600 joules of work every second.
-- 600 joules per second = 600 watts .
The average acceleration in 0.67 m/s^2.
The average acceleration is calculated as change in velocity/time
a=(247*5/18)/(1.7*60)
=68.61/102=0.67 m/s^2
Therefor the average acceleration of the object is 0.67 m/s^2
