that force A is of size 3 N and force B is of size 4 N . that the resultant force R will always be of size 7 N.?
That will be true only if the two forces are in the same direction.
Your grammar is difficult to understand. Sentences should begin with a capitalized word. Yours are dependent clauses and are not a proper question or sentence.
No, the resultant force R will not always be of size 7 N. The resultant force is determined by the vector sum of force A and force B. In this case, the magnitude of the resultant force R is given by the formula |R| = sqrt(|A|^2 + |B|^2 + 2|A||B|cosθ), where |A| and |B| are the magnitudes of force A and force B, and θ is the angle between the two forces.
If the angle between force A and force B is 0 degrees (they are acting in the same direction), then the magnitude of the resultant force R will be |R| = sqrt((3^2 + 4^2 + 2(3)(4)cos0)) = sqrt(9 + 16 + 24) = sqrt(49) = 7 N.
However, if the angle between force A and force B is any other value, then the magnitude of the resultant force R will be different.
To determine the resultant force of two forces, you need to use vector addition. The magnitude (size) of the resultant force depends on the directions and magnitudes of the component forces.
To find the resultant force when force A is 3 N and force B is 4 N, follow these steps:
1. Draw a vector diagram: Draw a vector representing force A with a magnitude of 3 N. Then draw another vector representing force B with a magnitude of 4 N. Arrows can be used to represent the direction of the forces. Make sure the vectors are placed with their tails at the same point.
2. Add vectors using the head-to-tail method: To add the vectors, start by placing the head of vector B at the tail of vector A. Then draw a new vector from the tail of vector A to the head of vector B. This new vector represents the resultant force R.
3. Measure the length of resulting vector: Measure the length of the resultant vector using a ruler or scale. The length of the vector represents the magnitude of the resultant force.
In this case, since the vectors A and B have magnitudes 3 N and 4 N respectively, and they are added head-to-tail, the resultant vector R should have a magnitude of 7 N. Therefore, the size of the resultant force R will always be 7 N when force A is 3 N and force B is 4 N.
It's important to note that the direction of the resultant force also matters. If the forces are acting in the same direction, the resultant force will have a value of 7 N. However, if the forces are acting in opposite directions, the resultant force will have a value of 1 N (4 N - 3 N).