Name: Lever: Principle of Moments and Mechanical Advantage
Uploaded: 2019-07-19
Duration: 6 min 29 s
Description: Engineers use a lever to magnify the force applied to an object. On what principle a lever works, and how to calculate the mechanical advantage of a lever? L...

Question

A block and tackle system has the velocity ratio

3

. Draw a labelled diagram of the system indicating the points of application and the directions of load and effort. A man can exert a pull of

200 kgf

. What is the maximum load he can raise with this pulley system if its efficiency is

60 %

?

Accepted Answer

Given,
The velocity ratio $V . R = n (number of pulleys) = 3$
Hence, number of pulleys $= 3$
Below is a labelled diagram of the system indicating the points of application and the directions of load $L$ and effort $E$ :

We know that, Efficiency $η = 1 - \frac{W}{nE}$
Given, Effort $= 200 kgf$ ,
$Efficiency = 60 % = 0.6$
Substitute the values in the formula for efficiency we get,
$0.6 = 1 - \frac{W}{3 \times 200}$
$\frac{W}{600} = 1 - 0.6 W = 600 \times 0.4 W = 240 kgf$
As we know,
$L o a d = (n \times E) - W L o a d = (3 \times 200) - W$
$Load = 360 kgf$ .

A block and tackle system has the velocity ratio $3$ . Draw a labelled diagram of the system indicating the points of application and the directions of load and effort. A man can exert a pull of $200 kgf$ . What is the maximum load he can raise with this pulley system if its efficiency is $60 %$ ?

Important Questions on Machines

Learn and Prepare for any exam you want !

A block and tackle system has the velocity ratio 3. Draw a labelled diagram of the system indicating the points of application and the directions of load and effort. A man can exert a pull of 200 kgf. What is the maximum load he can raise with this pulley system if its efficiency is 60%?

Important Questions on Machines

Learn and Prepare for any exam you want !

A block and tackle system has the velocity ratio $3$ . Draw a labelled diagram of the system indicating the points of application and the directions of load and effort. A man can exert a pull of $200 kgf$ . What is the maximum load he can raise with this pulley system if its efficiency is $60 %$ ?