Kinetic frictions, pulleys, and Newton's third law

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SUMMARY

The discussion focuses on calculating the acceleration and tension in a system involving two blocks connected by a string over a frictionless pulley. Block A, with a mass of 2.7 kg, experiences a kinetic friction force of 5.7 N, while Block B has a mass of 3.7 kg. The equations of motion provided include ƩFx=ma(x) and ƩFy=ma(y), which are essential for solving the problem. The user is on the right track by setting up the equations for the net forces acting on both blocks.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Basic knowledge of forces, including tension and friction
  • Familiarity with free body diagrams
  • Ability to solve linear equations
NEXT STEPS
  • Calculate the acceleration of the blocks using the equation a(x)=ƩFx/m
  • Determine the tension in the string using the equation Ft=Fg-Ft
  • Explore the effects of varying the mass of the blocks on acceleration and tension
  • Review concepts related to static vs. kinetic friction in similar systems
USEFUL FOR

Students studying physics, particularly those focusing on mechanics, as well as educators looking for practical examples of Newton's laws in action.

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Homework Statement


Block A and B are connected by a string passing over an essentially frictionless pulley. (Block A is on a horizontal plane, while block B is suspended in the air) When the blocks are moving block A experiences a force of kinetic friction of magnitude 5.7N. If mA= 2.7kg and mB= 3.7kg calculate the magnitude of:
(a) The acceleration of the blocks
(b) The tension in the string


Homework Equations


ƩFx=ma(x)
ƩFy=ma(y)
a(x)= ƩFx/m
Fnet(a)= Ft=Fk
Fnet(b)= Fg-Ft
Ft(b)=Ft(a)



The Attempt at a Solution


ƩF(a)= Ft-Fk
= Ft- 5.7N
ƩF(b)= Fg-Ft
= mg-Ft
=(3.7kg)(9.8N)-Ft
=36.26N-Ft
 
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