Resultant Force
In I/GCSE Physics, In order to understand Newton’s Laws we first must understand what a Resultant Force is. A Resultant Force is the Force that is left after we account for all of the Forces. So, if an object is being pushed with 7N of Force to the right and 3N of Force to the left the resultant force would be 4N to the right.
So, how do we calculate weight in I/GCSE Physics?
In order to do that we are going to have to understand a little more about Forces: a Force acts as a push or pull on an object, whether that be away from or towards the object applying the Force. The Earth has a Gravitational Field Strength (GFS) of 10N or ten Newtons, meaning that the Earth’s Gravitational Field will apply ten Newtons of force on an object, in this case it will be a pulling Force; this is what we must know in order to calculate weight on earth.
Weight is relative to a planet’s Gravitational Field. Meaning, the same object will have a different weight depending on the GFS of the planet. Let’s calculate it: we know that the GFS of Earth is 10N, meaning that for every one kg of mass there will be 10N of Force. Hence, we must times our Mass by 10 in order to calculate our Weight on Earth.
Example
A box is being pushed on opposing sides by Tom and Jimmy. Tom is pushing with 8N, and Jimmy is pushing with 12N. Who will succeed in moving the box away from himself and towards the other person according I/GCSE Physics?
Diagram:
Jimmy is pushing with 4N more Force than Tom, therefore our resultant Force is pushing with 4N towards the left: Jimmy’s Force – Tom’s Force (the smaller force minus the larger force) = 12 – 8 = 4. It truly is a single step question.
Challenges:
a) A prototype jetpack you have invented bugs out and starts pushing you with 20N Force upwards, rather than the 50N it is supposed to be pushing you with. Do you still have enough force to overcome Earth’s GFS? Or if you’re going to plummet to your death?
Formula for Resultant Force: aN ± bN = cN (Dir. 1’s F ± Dir. 2’s F = Resultant Force)
End of this topic!
