Find the direction and magnitude of the resultant forces

In summary, the two given forces of 25 lbs and 40 lbs result in a net force of 51 lbs with a direction of 29 degrees from the positive x-axis. This can be calculated using the components of the forces and the cosine and sine laws.
  • #1
dancer1311
1
0
1. Two forces of magnitude 25 pounds and 40 pounds act on an object. The force of 40lb acts along the positive x-axis, and the force of 25lb acts at an angle of 80 degrees with the positive x-axis. Find the direction and magnitude of the resultant force. Round the direction and magnitude to the nearest whole number.



2. The answer is suppose to be direction: 29 degrees and magnitude 51lb



3. i thought it was suppose to be 65(cos30i + sin30j)
which got me 65[tex]\sqrt{}3[/tex] divided by 2 i plus 65 divded by 2
but this doesn't give me the correct answers.
 
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  • #2
From where you are reaching at "65(cos30i + sin30j)"?

<40,0> + <other force vector_x, other force vector_y> = ?
 
  • #3
F1: 40 lbs, along x-axis

F2: 25 lbs, 80 degrees from x-axis.

Separating out the components, we have:

x-axis component = 40 + 25*cos(80) = 40 + 4.34 = 44.34 lbs

y-axis component = 25*sin(80) = 24.62 lbs

Net force = sqrt( x^2 + y^2) (you can do the math) and the angle is tan-1*(24.62/44.34).
 
  • #4
Since both rootX and mugaliens divided into components, here is a direct way: draw the 25 lb force as starting at the tip of the 40 lb force and you have a triangle with sides of length 25 and 40 and angle between them 180- 80= 100 degrees. Use the "cosine law" to find the length of the third side, the magnitude of the resultant force, and use the "sine law" to find the angle that third side makes with the 40 lb force.
 

Related to Find the direction and magnitude of the resultant forces

1. What is the purpose of finding the direction and magnitude of resultant forces?

The purpose of finding the direction and magnitude of resultant forces is to determine the overall effect of multiple forces acting on an object. This information is important in understanding the motion and equilibrium of the object.

2. How do you calculate the direction and magnitude of resultant forces?

To calculate the direction and magnitude of resultant forces, you need to first determine all the individual forces acting on the object and their respective magnitudes and directions. Then, you can use vector addition or trigonometric methods to find the resultant force.

3. What is the difference between direction and magnitude of resultant forces?

The direction of resultant forces refers to the angle or direction in which the overall force is acting, while the magnitude refers to the strength or size of the overall force. Both components are necessary in fully describing the resultant force.

4. Can the direction and magnitude of resultant forces be negative?

Yes, the direction and magnitude of resultant forces can be negative. This indicates that the overall force is acting in the opposite direction or has a negative value in terms of magnitude. It is important to consider both positive and negative values when calculating resultant forces.

5. How can finding the direction and magnitude of resultant forces be applied in real-life situations?

Finding the direction and magnitude of resultant forces has many practical applications, such as in engineering, physics, and sports. For example, engineers use this concept to design structures that can withstand external forces, while athletes use it to optimize their movements and achieve maximum performance.

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