A skier of mass m enters an exit slope with known speed VO. She needs to stop before a distance d in order to avoid crashing into spectators. If the exit slope makes an angle theta with the horizontal, what minimum constant friction force must the skier apply to come to rest before reaching the spectators?

A skier of mass m enters an exit slope with known speed VO. She needs to stop before a distance d in order to avoid crashing into spectators. If the exit slope makes an angle theta with the horizontal, what minimum constant friction force must the skier apply to come to rest before reaching the spectators?