Question

Explain the following text primarily based on the surrounding page content:
A lever with an effort arm of 10 meters and a load arm of 2 meters is used to lift an object weighing 220 Newtons to a height of 4 meters. If 400Joules of work is done, how much force must have been applied?(1 point)
Responses

4000 N
4000 N

100 N
100 N

800 N
800 N

1600 N
1600 N

Answer 1

Step through the physics and you see a contradiction in the question.

1. Mechanical advantage (ideal lever):
- effort arm = 10 m, load arm = 2 m → mechanical advantage = 10 / 2 = 5.
- For static equilibrium (ideal, no losses): Fe × 10 = 220 × 2 → Fe = (220×2)/10 = 44 N.

2. Distance and work:
- To lift the load 4 m, the effort end travels de = (effort arm / load arm) × 4 m = 5 × 4 = 20 m.
- The work required to raise the load (gain in gravitational potential) is W = weight × height = 220 N × 4 m = 880 J.
- With an ideal lever, work in = work out, so the effort must supply 880 J. That matches Fe × de = 44 N × 20 m = 880 J.

3. The given “400 J of work is done” is inconsistent:
- If only 400 J were supplied at the effort, Fe = 400 J / 20 m = 20 N — but that would not lift the 220 N load by 4 m (400 J < 880 J).
- So either the 400 J value is wrong or the system is not ideal (with energy losses), but with the data given you cannot get any of the listed answer choices.

Conclusion: none of the multiple-choice options is correct. For an ideal lever that actually lifts the object 4 m, the required effort force is 44 N (and the work needed is 880 J). If you forcefully insist on using the stated 400 J, the effort would be 20 N — but that would be insufficient to achieve the 4 m lift.