Question

A supari cutter is shown in the figure. Calculate the minimum effort(in Newton) required to lift the load of $4kg$ .(Figure is not to the scale)

A. $2.5$
B. $3.5$
C. $4.5$
D. $5.5$

Answer 1

Hint:This problem is based on the mechanical advantage topic. In this we will learn about effort and load. The applied force to bring the desired change to the position to push or pull the load is known as effort whereas load is defined as the heavy or a bulky object that requires effort to push or pull. Both load and effort have S.I as newton $\left( N \right)$ .The mechanical advantage is defined as the ratio of load lifted by a machine to the effort applied on the machine and also greater the value of mechanical advantage easier is the work done.

Formulas used:
$M.A = \dfrac{L}{E}$ ……….. $\left( 1 \right)$
And also,
$M.A = \dfrac{{{d_E}}}{{{d_L}}}$…………$\left( 2 \right)$
Comparing equation $\left( 1 \right)$ and equation $\left( 2 \right)$ we get
$E \times {d_E} = L \times {d_L}$
Effort $ \times $ Effort arm = Load $ \times $ Load arm………….$\left( 3 \right)$

Complete step by step answer:
For supari cutter,
Effort $ \times $ Effort arm = Load $ \times $ Load arm
$E \times {d_E} = L \times {d_L}$ ……..$\left( 4 \right)$
On substituting the given data in above equation we get,
$E \times 96 = 4 \times 6 \times 10$
On simplifying the above equation we get,
$E = \dfrac{{4 \times 6 \times 10}}{{96}}$
$\Rightarrow E = \dfrac{{240}}{{96}}$
$\therefore E = 2.5N$
Therefore the minimum effort required is $2.5\,N$.

Hence, correct option is A.

Note:The transfer of mechanical work from one part of a device to the other part of the device is carried out by the machines. The main purpose of the machines is to produce force and control the direction and the motion of force, but machines cannot create energy.The ability of the machines is measured by two factors namely mechanical advantage and the efficiency. The mechanical advantage is a dimensionless quantity because it doesn’t have a unit.