Two blocks are at rest on a horizontal frictionless surface with a compressed spring between them.The 5.0-kg block accelerates when the string holding the system in compression is cut and the 10-kg box accelerates in the opposite direction.What is the magnitude of the force from the expanding spring on the 10-kg box when the 5.0-kg box is undergoing an acceleration of 9.0 m/s²? A) 22.5 N B) 90 N C) 135 N D) 45 N E) 0 N

Question

Quizplus · Accepted Answer

The force on the 5.0-kg block is F = ma = 5.0 kg * 9.0 m/s² = 45 N. By Newton's third law, the force on the 10-kg block is equal in magnitude and opposite in direction, so it is also 45 N.

Two Blocks Are at Rest on a Horizontal Frictionless Surface