Question

Jon pushes a lawnmower with a force of 50.0 N directed at 50 degrees from the horizontal. The lawn mower moves 90.0 m. If Jon took 10.0 minutes to mow 90.0 m of grass, what was his power in SI units?

Answer 1

F = force by which Jon pushes the lawnmower = 50.0 N

θ = Angle of the force applied with the horizontal = 50 degrees

d = displacement of the lawnmower due to force applied = 90.0  

W = work done on the lawnmower = ?

work done on the lawnmower is given as

W = F d Cosθ

inserting the values

W = (50.0) (90.0) Cos50

W = (4500) Cos50

W = 2892.54 J

t = time taken by Jon to mow the lawnmower = 10.0 minutes = 10.0 x 60 sec = 600 sec                                           (Since 1 min = 60 sec)

Power is given as

P = W/t

inserting the values in the above formula

P = 2892.54/600

P = 4.82 Watt