A balanced lever has two weights on it, one with mass #2 kg# and one with mass #8 kg#. If the first weight is # 4 m# from the fulcrum, how far is the second weight from the fulcrum?

2 Answers
Mar 30, 2018

Answer:

#1m#

Explanation:

The concept that comes into use here is torque. For the lever to not tip over or rotate, it must have a net torque of zero.

Now, the formula of torque is #T=F*d#.

Take an example to understand, if we hold a stick and attach a weight at the front of the stick, it doesn't seem too heavy but if we move the weight to the end of the stick, it seems a lot heavier. This is because the torque increases.

Now for the torque to be same,
#T_1=T_2#

#F_1*d_1=F_2*d_2#

The first block weighs 2 kg and exerts approximately #20N# of force and is at a distance of 4m

The first block weighs 8 kg and exerts approximately #80N#

Putting this in the formula,

#20*4=80*x#

We get that x= 1m and hence it must be placed at a distance of 1m

Mar 30, 2018

Answer:

The distance is #=1m#

Explanation:

www.thoughtco.com

The mass #M_1=2kg#

The mass #M_2=8kg#

The distance #a=4m#

Taking moments about the fulcrum

#M_1xxa=M_2xxb#

The distance is

#b=(M_1xxa)/(M_2)=(2*4)/(8)=1m#