Question

Which of the following describes what happens to effort force when a car jack increases the distance over which the force is exerted?

Force will be decreased.


Force will be increased.


Force will be unchanged.


Force will depend on the mass of the object.

Answer 1

Also How is work affected when an object is lifted straight up instead of using a ramp?


Work will increase.


Work will decrease.


Work will stay the same.


Work will depend on mass of the object.

Answer 2

When using a car jack the effort force (force you put in to do the work) is decreased. This is the reason why car jacks and levers etc are useful. However, the work done is the same.

Using a jack you may be able to exert a force of 10000N on the car and raise it by 0.1m. If the jack gives you a mechanical advantage of 100, then you only need to exert a force of 100N on/through the jack to do this, BUT you will have to apply that force across an effective distance (by pumping a lever or whatever) of 100*0.1 = 10m.

You should know that work done is (effort) force * distance, so the work done is the same.

This applied again in your second question. Effort force is decreased because you are not supporting the full weight of the object, but you must move it further by the same factor to raise it to the same height, so the work done is again the same.

Answer 3

um i dont quite understand that :/ im sorry

Answer 4

mmmm...
1) force decreased
2) work stays the same (disregarding friction)