Imagine if you’re trying to move a heavy box. Carrying it up is a bad idea since it might hurt your back, so you decide to push it. You find that you need to exert strength to get the box to start moving, i.e. you are exerting a force on the box.
Force is simply an action that causes a body to accelerate.
In Statics, we deal mainly with things that are stationary (hence the name “statics”). So the next question is: how does an object remain stationary when there are forces acting on it? Well, we have reaction forces balancing the action forces, such that the net force is zero.
Imagine if you’re trying to move a heavy box. Carrying it up is a bad idea since it might hurt your back, so you decide to push it. You find that you need to exert strength to get the box to start moving, i.e. you are exerting a force on the box.
Force is simply an action that causes a body to accelerate.
In Statics, we deal mainly with things that are stationary (hence the name “statics”). So the next question is: how does an object remain stationary when there are forces acting on it? Well, we have reaction forces balancing the action forces, such that the net force is zero.
For example, you might find it impossible to move a 100 kg box no matter how hard you try, because the frictional reaction force is counteracting your pushing action force. We will be covering reaction forces more in Chapter 2.
Force is a vector, meaning it has both magnitude and direction. Therefore it can be split or resolved into its rectangular components in the x- and y- directions, using the sine and cosine functions:
The unit for force is Newtons (N). And yes, this is the guy who discovered gravity by observing a falling apple.
Most static problems have more than one force acting on a body. It is useful to obtain the resultant force acting on the body, and there are two methods to do this:
The resultant of 2 forces in the same direction is just the direct sum of both forces. The idea behind this method is to:
This method works by:
We’ve covered quite a bit of theory on forces already! Let’s look at an example now.
For example, you might find it impossible to move a 100 kg box no matter how hard you try, because the frictional reaction force is counteracting your pushing action force. We will be covering reaction forces more in Chapter 2.
Force is a vector, meaning it has both magnitude and direction. Therefore it can be split or resolved into its rectangular components in the x- and y- directions, using the sine and cosine functions:
The unit for force is Newtons (N). And yes, this is the guy who discovered gravity by observing a falling apple.
Most static problems have more than one force acting on a body. It is useful to obtain the resultant force acting on the body, and there are two methods to do this:
The resultant of 2 forces in the same direction is just the direct sum of both forces. The idea behind this method is to:
This method works by:
We’ve covered quite a bit of theory on forces already! Let’s look at an example now.