Question

In a screw jack, a lever of length 2 m is rotated once to lift the car of 1000 kg by 20 cm. What is the effort applied to the simple machine?

• A. $\frac{50}{\pi }$ kg wt
• B. $\frac{100}{\pi }$ N
• C. $\frac{100}{\pi }$ kg wt
• D. $\frac{50}{\pi }$ N

Answer 1

The correct option is A

$\frac{50}{\pi }$ kg wt

Step 1, Given data

Length of the lever (l) = 2 m

Weight of the car (Load L) = 1000 kg

Displacement of the car (P) = 20 cm = 0.2 m

Step 2, Finding the effort

For the lever total displacement will be $2\pi l$

Now, From the principle of the lever

We can write

$L\times P=Effort\times 2\pi l$

Putting all the values

$Effort=\frac{1000kg\times 0.2m}{2\times \pi \times 2m}=\frac{200}{4\pi }=\frac{50}{\pi }kgwt$

Hence the correct option is (A).