High School Physics : Calculating Force
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Example Questions
Example Question #11 : Calculating Force
Miguel pushes a box with 
We need to look at the net force, which is the sum of the other forces:
Since Alexis and Miguel are pushing with the same value but in opposite directions, make one of these forces negative:
Therefore, the net force upon the object is 
Example Question #11 : Net Force
A dog bites down on a chew toy with 
We need more information to solve
Use Newton's third law to solve this question. The force of the dog on the chew toy is equal in magnitude, but opposite of direction, to the force of the chew toy acting on the dog.
That means that 
Using our given values for find the force of the chew toy.
Example Question #13 : Calculating Force
If the mass of the object is 
The normal force is always perpendicular to the surface upon which the object is moving, and is pointed away from said surface. That means we are looking for the value for Z in the diagram.
Observe that Z and Y are equal, but opposite forces.
If we can solve for Y, then we can find Z.
We can use our understanding of trigonometry to find an equation for Y.
If we plug in 
Since we are solving for Y, we can multiply both sides by W.
Now that we know an equation for Y, we can return to our original equation to solve for Z.
From here, we can use Newton's second law to find the value of W, the total force of gravity.
Substitute this into our equation for Z.
Now we can solve for Z using the values given in the question for the angle, mass, and gravity.
Example Question #14 : Calculating Force
If the mass of the object is 
The normal force is always perpendicular to the surface upon which the object is moving, and is pointed away from said surface. That means we are looking for the value for Z in the diagram.
Observe that Z and Y are equal, but opposite forces.
If we can solve for Y, then we can find Z.
We can use our understanding of trigonometry to find an equation for Y.
If we plug in 
Since we are solving for Y, we can multiply both sides by W.
Now that we know an equation for Y, we can return to our original equation to solve for Z.
From here, we can use Newton's second law to find the value of W, the total force of gravity.
Substitute this into our equation for Z.
Now we can solve for Z using the values given in the question for the angle, mass, and gravity.
Example Question #15 : Calculating Force
The force acting upon a crate is 
For this problem use Newton's second law:
We are given the total force and the mass, allowing us to solve for the acceleration.
Example Question #16 : Calculating Force
Two dogs pull on a bone. One pulls with 
We must know the mass of the bone to solve
Force is a vector quantity, meaning that both magnitude and direction are important factors. Net force is calculated by summing all of the forces acting on an object.
For this question, we will assign "to the right" as the positive direction and "to the left" as the negative direction. Under these conditions, we can add the given forces to find the net force.
This means that it has a net force of 
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