A student of mass stands motionless on a large sheet of perfectly frictionless ice…
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A student of mass 65kg stands motionless on a large sheet of perfectly frictionless ice that covers an outdoor skating rink. Treat Earth as a uniform sphere of mass 5.97×1024kg and radius 6.37×106m. Ignore all objects other than the student and Earth.
(a) Identify the pair of forces that act between the student and Earth in this situation.
(b) Describe the magnitude and direction of each force in the pair you identified in part (a).
(c) Using appropriate physical principles, explain why the student readily accelerates toward Earth while the motion of Earth toward the student is imperceptible.
(d) If the system is re-defined to include both the student and Earth, discuss whether the forces you named in part (a) are internal or external to that system and state the consequence for the net external force on the system.