F=Ma... Does This Mean Tha Acceleraton Is Necessary To Have Force? Read Detals...

[Sachin114]

suppose a machine is constantly applyng a force equal to 100 N to a concrete wall. Neither the machine nor the wall is moving. In this case what will be the value of M and A... Sorry if this is a stupid question... I am a nube to physics...

[Old_Geezer]

Units can be described/defined in different ways. One definition will be official. If you have mass and it is accelerating in a vacuum then you may calculate the force that's causing it. It doesn't imply that the reverse is true and you can only get force if something is speeding up.

Consider the case where two opposing forces are acting on a body in opposite directions. They cancel out, but still exist. However there is no resultant force. Or where a force isn't enough to overcome friction, for example. The force still exists.

[Sachin114]

well then does F-ma applicable only in cases where objects are moving? and what is the formula for forces acting under static conditions....

[Ninefingers]

for a in many cases read "acceleration due to the force of gravity" around 9.8 ms(-2)

[Old_Geezer]

Been a long time since I did physics at school so I'll leave that to the physicists and structural engineers. But it can get complex with some forces changing over time as friction will. I suspect that the key is the resultant force once you've drawn all the arrows (representing force) on your diagram and performed the maths to find out what's the overall result.

[Sachin114]

thats right nine fingers.. but what about an apparatus set in space?

[fiction-factory]

F=ma tells us that if there is no acceleration (a=0) then there is no force. Note that acceleration can be 0 when objects are moving at a constant speed. This does not mean that there can be no forces relating to static bodies.
Consider a block of stone resting on the ground. There is a force downwards due to gravity; this is equal to its mass x acceleration due to gravity (circa 9.8m/s/s). There is a corresponding upward force from the ground which cancels this out. The net result is the object is static

[EDDIE51]

If this was set up in a vacuum (space) nothing would be affected. It is the same as Newton's third Law that you mentioned in your last question. The atmosphere does not come into the equation.

[jim360]

The "F" on the left is the sum over all forces acting on a body. If that sum is non-zero then the body in question will accelerate. If that sum is zero then the forces are still acting, but do so in balance.