Tag: pulley

Questions Related to pulley

In a fixed pulley 

physics machines levers and pulleys pulley pulleys

  1. load and effort are equal

  2. load is greater than effort

  3. load is less than effort

  4. both have no relation

Show answer
Correct Option: A

A block and tackle system has the velocity ratio $3$. A man can exert a pull of $200kgf$. What is the maximum load he can raise with this pulley system if its efficiency is $60\%$

physics machines levers and pulleys pulley pulleys

  1. $250 kgf$

  2. $260 kgf$

  3. $350 kgf$

  4. $360 kgf$

Show answer
Correct Option: D
Explanation:

$Mechanical advantage = Velocity Ratio \times Efficiency $
$M.A = 3 \times \dfrac{60}{100} = 1.8$
$M.A = \dfrac{load}{effort} $
$\therefore load = M.A \times effort$
$\Rightarrow 1.8 \times 200 = 360kgf$

It is easy to draw water from a well when the rope passes over a pulley than drawing it directly. Because:

physics machines levers and pulleys pulley pulleys

  1. pulley adds more force

  2. pulley decreases the weight of the bucket

  3. pulley has a mechanical advantage of more than one

  4. pulley changes the direction of force

Show answer
Correct Option: D

A force of $250 N$ is required to lift a $75 kg$ mass through a pulley system. In order to lift the mass through $3 m$, the rope has to be pulled through $12m$. The percent efficiency of system is

physics machines levers and pulleys pulley pulleys

  1. $50$

  2. $75$

  3. $33$

  4. $90$

Show answer
Correct Option: B
Explanation:
Height lift was $h=3m$
Work done by the force is $W=Fd=250\times 12=3000Joule$

Work against the gravity i.e. $increase $ in potential energy of the  mass is $E=mgh=75\times 10\times 3=2250Joule $

so efficiency will be $\eta \times 100=\dfrac{E}{W}\times 100$% = $75$%

By using a wheel-and-axle arrangement,you can :

physics a little effort, lot of work levers and pulleys pulley pulleys

  1. Magnify the speed

  2. Magnify movement

  3. Effort can be moved through a greater distance by attaching a handle

  4. All of the above

Show answer
Correct Option: D

It is easy to draw water from a well when the rope passes over a pulley than drawing it directly. Because :

physics machines levers and pulleys pulley pulleys

  1. Pulley adds more force

  2. Pulley decreases the weight of the bucket

  3. Pulley has a mechanical advantage of more than one

  4. Pulley changes the direction of force

Show answer
Correct Option: D