Two blocks are connected by a massless string over a frictionless pulley with ne
ID: 1916313 • Letter: T
Question
Two blocks are connected by a massless string over a frictionless pulley with negligible mass as shown in the figure below. The block m1=3 kg lies on a horizontal surface and is connected to a spring of force constant k = 200 N/m. The system is released from rest when the spring is unstretched. If the hanging block of mass m2 = 40 kg falls a distance h = 28 cm before coming to rest: Calculate the coefficient of the kinetic friction between the block of mass m1 and the surface. What is the change in the thermal energy? What is the maximum distance the block of mass m2 will move if the surface is frictionless?Explanation / Answer
fk = µk x N T = m2 x g = 800 N Now T = k x h + fk 800 = 200 x (28/100) + µk x 30 or, µk = 744 / 30 = 24.8 Change in thermal energy = 0.5 x 200 x (0.28)2 + 24.8 x 30 (0.28)2 = 66.16 J B) Let x be the maximum distance moved by block. Apply energy conservation law and you will get it.