# Free Body for object on vertical wall, Applied force, Torque required for motion [closed]

I am trying to understand how to create a correct Free Body diagram and understand formula used to forces acting on object (i.e. a robot with 4 wheels) that is "placed" on vertical surface such as a steel wall.

Normally, I have seen a lot of example on internet regarding a books being "pushed" onto the wall and the book is 'motionless' or stuck.

Q1) However, what would happen if a magnet attached to the object created a pulling force (towards the wall, assuming the wall is made of steel).

Q2) Also, is 'motionless' is same as equilibrium? Can object be in equilibrium but still be moving where we can evaluate force them Sigma Fx = 0 and Sigma Fx=0

Q3) Also, how to incorporate in free body diagram that the object is attempting to move upwards and will accelerate in the upward direction with its own effort (motors etc) no external forces but torque.

Q4) Also, would Friction Force on the wheels of the object would act in opposite direction of the direction of moving wheels?

Q5) Can you determine Torque required to move the wheels on the object to move the object using Friction Force x Wheel radius = Torque? Where: Friction Force, Fa=μ*Na Na is Normal force i.e force of surface on object /wheels μ = coefficient of friction Is this a real formula?

Q6) Also,is Fa=μ*Na applicable even when the object is moving?

The setup of the concept and my solution via formula is attached via photo attached here.

Q7) How to calculate acceleration if you know end velocity and can you assume 0 to end velocity is reached in 1 sec?

Q8)I hope someone can answers my questions so I understand the concepts and theory.

Q9) If you know a Force in terms of Nm how can you convert that more practical format like Kg or Psi etc? Or not possible?

I thank Jared for explaining the implications of Position 1,2 and 3 from by previous post and have restated the questions and providing formula relationship between friction and normal force and suggesting to use Free Body Diagram.

• What would be different between the force of gravity and the force of a magnet? Having said that, as shown your crawler won't be able to negotiate the transition between the wall and the ceiling. It's almost guaranteed to fall off, unless you make the transition curved or you build some sort of movable magnetic latch to hold on while it transitions. May 29, 2015 at 21:35
• Its just a concept. Have not considered the transition.Just wanted to understand the forces acting the directions. May 31, 2015 at 14:59
• Fair. Good look with your project! May 31, 2015 at 15:01
• Also.I wanted to add : The Force of the magnet is the force of attraction between the magnet fitted on the robot and the steel wall. Its pulling the robot towards the wall. The force of gravity is pulling the machine down. May 31, 2015 at 15:19

The frictional force is determine by the normal force: $|F_{fr}| \approx \mu_s |N|$.