Calculating Time for a Person Pulling a Lawn Mower

[zaddyzad]

Homework Statement

A person pulls on a 20kg lawnmower with a force of 25.0N and moves the mower 4.50metes. The handle angle is 15* with the horizontal and μ=0.100.
a) Work done by person √ = 109J
B) Work done by friction √ = -85.3J
C) Find the time ?

Homework Equations

P= W/T = W*(constant velocity)

The Attempt at a Solution

I tried to use one of the power equations though I had 2 unknowns (P and T). I have no idea how to go about finding the time.

 

[gneill]

Homework Statement

A person pulls on a 20kg lawnmower with a force of 25.0N and moves the mower 4.50metes. The handle angle is 15* with the horizontal and μ=0.100.
a) Work done by person √ = 109J
B) Work done by friction √ = -85.3J
C) Find the time ?

Homework Equations

P= W/T = W*(constant velocity)

The Attempt at a Solution

I tried to use one of the power equations though I had 2 unknowns (P and T). I have no idea how to go about finding the time.

What's the net horizontal force on the lawnmower? What then is the motion? Can you think of a suitable kinematic equation to find the time given the distance traveled?

 

[zaddyzad]

Thank you very much for the help :D. Got it 5.89s