Two blocks are at rest on a horizontal frictionless surface with a compressed spring between them.The 15.0-kg block accelerates when the string holding the system in compression is cut and the 30.0-kg box accelerates in the opposite direction.What is the magnitude of the force from the expanding spring on the 30.0-kg box when the 15.0-kg box is undergoing an acceleration of 5.00 m/s²? A)37.5 N B)150 N C)225 N D)75.0 N E)0 N

Question

Quizplus · Accepted Answer

The force on the 15.0-kg block is F = ma = 15.0 kg * 5.00 m/s² = 75.0 N. By Newton's third law, the force on the 30.0-kg block is equal in magnitude and opposite in direction, so it is also 75.0 N.

Two Blocks Are at Rest on a Horizontal Frictionless Surface