Lesson 10/4

Establish a coordinate system

Draw a free body diagram that shows the forces acting on the girl as she travels down the slide

The three forces acting on the girl are the normal force, kinetic friction, and the girls weight.

mass = 45 kg

𝜇_s = 0.23

t = 1.0 s

𝜙 = 27°

v_i = 0 m/s

a =

v_f =

𝜭 =

Add forces in the y-direction to find F_Nmg

F_N + F_gy = F_net,y

F_N = -F_gy

F_N = -mg(sin𝜭)

F_{net, x} = F_gx - F_f

ma_x = mg(cos 𝜭) - 𝜇_sF_N

ma = mg(cos 𝜭) + 𝜇_smg(sin 𝜭)

a = g(cos 𝜭 + 𝜇_{s sin} 𝜭)

a= 9.8 m/s²)(cos 297 + 0.23)(sin 297)

2.4 m/s²

v_f = v_{i + at}

v_f = 0.0 m/s + (2.4 m/s²)(1.0 s)

2.4 m/s

Try yesterday's assignment