Free Body Diagram
Free-body Diagram is a simple diagram with arrows to represent the forces acting on the object. For example,
However, normally, we only draw out those forces that are used in the calculation.
In below Figure, block A and B are connected by light rope and the rope passes over frictionless and massless pulleys. Block A has a weight of 10.0 N and is placed on a rough horizontal surface with a frictional force of 5.0 N.
Given block B descends with an acceleration of 7.0 ms^(-2),
(a) Draw two separate free-body diagrams showing the forces acting on A and on B.
(b) (i) Calculate the tension in the rope connecting block A and B.
T – f = ma
T – 5 = 10/10 * 7
T = 12.0 N
(ii) Calculate the weight of block B.
W – T = ma
m * 10 – 12 = m * 7
m = 4.0 kg
W = mg = 40.0 N