physics power problem?

Question

you are trying to lose weight by working out on a rowing machine. each time you pull the rowing bar toward you, it moves a distance of 1.2m in a time of 1.5s. the readout on the display indicates that the average power you are producing is 82w. what is the magnitude of the force that you exert on the handle?

for some reason i keep getting the wrong answer...im not sure why, any help please
thanks

Answer 1

Work, measured in Joules is force times distance
Power is work divided by time
A watt is one Joule per second

so 82 Joules per second over a time of 1.5 seconds is
82*1.5
123 Joules per stroke

One Joule equals one Newton*meter
since the distance is 1.2 m, then
F*1.2=123
F=123/1.2
102.5 Newtons

j

Answer 2

Let m be the mass of the car, V its final speed, t the time during which its speed increases from 0 to V, P the required average power, then the work-kinetic energy theorem tells us that we should have mV^2/2=Pt (1) and so P=mVV/2t (2) Transform the speed in m/s, introduce the corresponding values in (2) in order to obtain P in joule/s. Your pocket computer will do the job.

Answer 3

I think that power = F* t
there fore 82 = 1.5 * F
F = 55 J

Answer 4

find work
Power = work / time
82W = work / 1.5s
work = 123 J

work = force * distance
123J = force * 1.2m
force = 102.5N