Question

Olympic skier Tina Maze skis down a steep slope that descends at an angle of 30∘ below the horizontal. The coefficient of sliding friction between her skis and the snow is 0.10.
I found Maze's acceleration which is 4.1 m/s^2. But how do you determine Maze's speed 4.0 s after starting?

Answer 1

net force on Maze during his sliding downwards motion

$F = mgsin30 - \mu mg cos30$

now we will have

$F = mg(sin30 - 0.10cos30)$

now to find the acceleration we will have

$a = \frac{F}{m}$

$a = g(sin30 - 0.10cos30)$

$a = 9.81(0.5 - 0.10(0.866))$

$a = 4.1 m/s^2$

now to find the speed after 4 s is given by kinematics

$v_f - v_i = at$

here we know that

$v_i = 0$

$v_f - 0 = 4.1(4)$

$v_f = 16.22 m/s$

so Maze speed after 4 s will be 16.22 m/s