A gardener pushes a lawn mower across a horizontal lawn by applying a constant force…
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A gardener pushes a 12kg lawn mower across a horizontal lawn by applying a constant force of magnitude 90N directed at an angle of 30∘ below the horizontal. The coefficient of kinetic friction between the mower and the grass is 0.15.
(a) Draw a clearly labeled free-body diagram showing all forces acting on the lawn mower.
(b) Determine the magnitude of the normal force exerted on the mower by the ground.
(c) Calculate the magnitude of the kinetic friction force acting on the mower.
(d) Determine the magnitude of the mower’s acceleration.
(e) The gardener keeps the force magnitude at 90N but now applies it at an angle θ above the horizontal instead of below. Derive an expression for the value of θ that will cause the mower to move at constant speed.