A snowboarder of mass 70 kg coasts horizontally across a nearly frictionless patch of…
PHYSICS · Multi-part · CBSE · Physics · Laws of Motion · Laws of Motion
Problem
A snowboarder of mass 70 kg coasts horizontally across a nearly frictionless patch of snow at 5 m/s when a stiff wind begins to blow uniformly toward the snowboarder’s left. At the same moment, the rider digs the edge of the board slightly into the snow so that a kinetic friction force of 30 N acts opposite the original direction of motion.
The wind exerts a steady 40 N force due south (to the rider’s left). Neglect air resistance other than the stated wind force.
(a) Qualitatively determine the direction of the net external force acting on the snowboarder–board system immediately after both forces begin to act.
(b) Describe the direction of the snowboarder’s acceleration at that instant and explain your reasoning.
(c) The snowboarder’s instantaneous velocity is still 5 m/s east (to the rider’s right). Explain how the velocity can have a different direction from the acceleration, and predict qualitatively how the velocity vector will evolve over a short time interval.