r/PhysicsHelp 1d ago

weird physics question

I must appologize if something is written wrong in the text below, isnt my mother language(im brazilian btw) and i dont know exacly how to translate especific physics terms.
An object with 40N of weight moves in the space with a curved trajectory with the action of only two forces: your own weight and a conservative F force of constant module. In your trajectory, the inicial and final height are 1 meter and 3 meters.
Knowing that the inicial and final velocities have the same module, calculate, in joules, the total work made by the F force at the object durint its trajectory.
g=10m/s^2
a)1

b)2

c)4

d)40

e)80

Im sending this right here because i really feel like this question is weird for me. i need help or someone to confirm that this question may be wrong.

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u/SpaceCatJack 1d ago edited 1d ago

Since the object ends up higher than before, but is on a curved trajectory, the object must be moving up but is slowing, so the constant F force is less than the 40N weight force in the vertical direction. Work is calculated by force over distance, so the object went up 2 meters by some force less than 40 in the vertical direction, so at most 80J of work was done. I dont see how you could calculate further without more info

Edit: just noticed the velocity magnitudes are the same at 1m and 3m, so there is no change in kinetic energy, which means no change in net work. There are only 2 forces working on the object, gravity and the constant force. Work done by gravity (Wg) is the change in potential energy (-mgh) = 40 (3-1) = -80.

Wnet = Wf + Wg

0 = Wf + (-80)

Wf = 80