The mass of a stroller and the child it carries is 21.1 kg. A woman pushes the stroller with a force of 121 N at an angle of 41.0° to the vertical. The stroller experiences a friction force of 4.0 N. What is the stroller's acceleration forward?

Newton's second law:

∑F = m*a Formula (1)

∑F : algebraic sum of the forces in Newton (N)

m : mass s (kg)

a : acceleration (m/s²)

We define the x-axis in the direction parallel to the movement of the stroller and the y-axis in the direction perpendicular to it.

Forces acting on the stroller

W: Weight of the stroller and the child : In y-direction downward

FN : Normal force : In y-direction upward

f = 4 N: Friction force: In x-direction opposite to the movement

P = 121 N Woman's force on the stroller, at an angle of 41.0° to the y-axis

x-y components of the F

Px = 121 N*sin41° = 79.38 N

Py = 121 N*cos41° = 91.32 N

Stroller's acceleration forward

We apply the formula (1)

∑Fx = m*a

Px - f = m*a

79.38 - 4 = (21.1) * a

75.38 = (21.1) * a

a = 75.38 / (21.1)

a = 3.57 m/s²