Asked by Dani

a person horizontally pushes a 25 kg couch. Applied force is 18N and average resistive force is 7N. its pushed from rest to a final speed of 2.3
what is the distance pushed
the time taken
and the power delivered to push couch
Answered by Damon
net push = 18 - 7 = 11 N
so
11 = m a = 25 a
so
a = 11/25 m/s^2

v = a t

so t = 2.3 * 25/11 = 5.23 s

and
average v = (0+2.3)/2 = 1.15 m/s
so

d = 1.15 * 5.23 = 6.01 meters

power = force * distance/ime
= 18 *6.01/5.23 = 20.7 Joules average power
Answered by dani
wouldn't time be 2.3 times 11/25 then?
thank you