Physics IMA AND LEVERS

Question

knowing the maximum lever length is 1 meter and the weights range from 10 g to 1kg, if you have a class 1 lever with a mechanical advantage of 1

a. what is the length between the fulcrum and effort force

b. what is the length between the fulcrum and resistance/load force

c. what is the mass of the weight and what is the force of gravity of that weight (F=M*A, 9=9.8M/S^2)

d. based on your mechanical advantage how much force do you need to use lift the weight using the lever?

Answer 1

Given:

Class I lever

Maximum range: 1 meter

Load range: 10 g to 1 kg

Required:

Force and mass at ideal mechanical advantage (IMA) = 1?

Solution:

Question a:

what is the length between the fulcrum and effort force?

A1: A class I lever is centered (pivoted) between force and resistance.

Thus, the fulcrum (pivot) position between the two ends determines the IMA, as follows:

Ideal Mechanical Advantage (IMA) = ratio of effort's arm / resistance arm

Denote the forces and lengths as follows:

Force effort by F_e

Resistance force by F_r

Length of Beam by L

Arm of F_e by L_e

Arm of F_r by L_r

The two governing equations of lengths and proportions of mechanical advantages are:

MA = L_e / L_r -------------------(1)

L = L_e + L_r -------------------(2)

At IMA = 1, L_e = L_r = L/2 = 0.5 meter

Question b:

what is the length between the fulcrum and resistance/load force?

This question is just another way of stating the previous question.

i.e., the arm of resistance L_r equals the arm of effort L_e, equals half the beam's length, because IMA is given as IMA = 1.

Therefore, the two arms = 0.5 meter

Question c:

what is the mass of the weight and what is the force of gravity of that weight (F=M*A, 9=9.8M/S^2)"

The question states Newton's second law of motion; F = m.a

The question also provides the gravitational acceleration g as 9.8 m/s². (g is the acceleration a)

Thus, for a maximal load of 1 kilogram, the force of gravity is given by the

F = m.a = 1 kg x 9.8 .m/s² = 9.8 N

m = 1 kg, the mass of the weight, which is given in the question.

Question d:

based on your mechanical advantage how much force do you need to use lift the weight using the lever?

This is again another restatement of the previous question, because IMA = 1, therefore L_e = L_r and F_e = F_r .

Force of resistance F_e = 9.8 N

What did we learn?

What is in the mind of the person posing the four question:

The question is geared to enforce the difference between mass and weight.

Mass is measured in kilograms.

Weight is measured in Newtons (kilogram x meter / second²⁾