Physics

posted by .

This is how the problem starts out:

A meter stick is placed with the fulcrum at the 50-cm mark.

If a 120-g mass is placed at the 25-cm mark and a 25-g mass at the 10-cm mark, where should a 500-g mass be placed to balance the system?

I thought that since the two masses (the 120 and the 25 ones) were on the same side of the fulcrum, you could add the two masses together and just use the longest distance from the fulcrum. Apparently (what my physics teacher told me) this is wrong.

Thanks!

  • Physics -

    No, you may not add the two masses
    the 25 grams is 40 cm from the fulcrum
    the 120 grams is 25 cm from the fulcrum
    so on that side you have
    25* 40 + 120 * 25 = 4000
    That is NOT the same as 145 * 40 !!!
    on the other side you have 500 grams a distance "x" from the fulcrum
    so
    500 x = 4000
    solve for x
    then remember that x is measured from the fulcrum at the 50 cm mark so the 500 grams must be located at the 50 + x cm mark

  • Physics -

    Okay. So in equation form it would look like this:

    d(3)=((120*25)+(25*40))/500
    which equals 8.

    So the fulcrum would be placed at the 58 cm mark, right?

    This is exactly what my friend did, I just couldn't remember what he wrote down or how he explained that concept. Thanks for all of your help, Damon!

  • Physics -

    Oops, I meant the 500g mass is placed at 58 cm. I was thinking fulcrum because of my next problem, and I got the two terms mixed in my head. Thanks again!

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. torque

    A meterstick is found to balance at the 49.7 cm mark when placed on a fulcrum. When a 50.0g mass is attached at the 10.0cm mark, the fulcrum must be moved to the 39.2 cm mark for balance. What is the mass of the meterstick?
  2. Physics 1

    A meter stick has a mass of 200g and its center of gravity is at the 50.0 cm mark. If 150g is attached to the stick at the 10 cm mark, where would an upward force on the stick need to be placed to balance the stick and the added mass?
  3. Physics*

    A meter stick is found to balance at the 49.7-cm mark when placed on a fulcrum. When a 70.0-gram mass is attached at the 16.0-cm mark, the fulcrum must be moved to the 39.2-cm mark for balance. What is the mass of the meter stick?
  4. physic

    a uniform meter stick of mass 100g is pivoted about the 30 cm mark. a mass of 200 g is placed at the 10 cm mark. where should a mass of 50 g be placed so that the meter stick balance horizontally?
  5. physics( i have no idea how to go about gettign th

    a uniform meter stick of mass 100g is pivoted about the 30 cm mark. a mass of 200 g is placed at the 10 cm mark. where should a mass of 50 g be placed so that the meter stick balance horizontally?
  6. Physics

    A uniform meter stick balances on a fulcrum placed at the 40 cm mark when a weight W is placed at 30 cm mark. What is the weight of the meter stick?
  7. Physics

    A uniform meter stick balances on a fulcrum placed at the 40 cm mark when a weight W is placed at 30 cm mark. What is the weight of the meter stick?
  8. physics

    A meter stick is found to balance at the 47.3cm mark when placed on a fulcrum. When a 45.7g mass is attached at the 10.5cm mark, the fulcrum must be moved to the 38.5cm mark for balance. What is the mass of the meter stick?
  9. Physics

    A meter stick has mass 39 g, and has a pivot placed at the center at the 50 cm mark. A mass of m1 is place at the 5 cm mark. Another mass of 10 g is placed at the 70 cm mark. What mass m in grams has to be placed at the 80 cm mark …
  10. physics

    A 1-kg rock is suspended from the tip pf a uniform meter at 0 cm mark so that the meter stick balances like a see-saw when the fulcrum is at 20 cm mark. what is the mass of the meter stick?

More Similar Questions