posted by Leah on .
A person pushes a 11.0 kg lawn mower at constant speed with a force of 76.0 N directed along the handle, which is at an angle of è = 41.0° to the horizontal. Calculate the normal force exerted vertically upward on the mower by the ground. Calculate the force the person must exert on the lawn mower to accelerate it from rest to 1.3 m/s in 2.0 seconds (assuming the same retarding force).
W = mg = 11kg * 9.8N/kg = 107.8N. =
Weight of lawn mower.
Fm = 107.8N @ 0deg. = Force of mower.
Fp = Fh = 107.8sin(0) = 0 = Force parallel to ground = Hor comp.
Fv = 107.8cos(0) = 107.8N. = Force perpendicular to ground.
a. Fn = Fv + Fap*sin41,
Fn = 107.8 + 76sin41 = 157.7N.=Normal force upward from ground.
b. a = (Vf - Vo) / t,
a = (1.3 - 0) / 2 = 0.65m/s^2.
Fap = 76 + ma = 76 + 11*0.65 = 83.15N.
= Force applied.