Tag: pulley

Questions Related to pulley

Two crowbars of lengths 5 m and 7 m are used to lift a boulder, using a small stone, as a fulcrum. Does it affect the effort required to lift the load?

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

  1. Yes

  2. No

  3. Maybe

  4. Sometimes

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Correct Option: A
Explanation:

Yes it effects the effort required to lift the load as a crow bar of 7 m length provides greater effort arm than a crow bar of 5 m length. Thus crow bar of 7 m length requires lesser effort.

A block of mass M on a horizontal smooth surface is pulled by a load of mass  M / 2  by means of a rope  AB and string BC as shown in the figure .The length and mass of the rope AB are L and  M / 2 respectively .As the block is pulled from A = L to AB = 0 its acceleration changes from 

physics machines levers and pulleys pulley pulleys

  1. $\frac{3g}{4}$ to g

  2. $\frac{g}{4} to\frac {g}{2}$

  3. $\frac{g}{4} to {g}$

  4. $\frac{3g}{2}$ to 2g

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Correct Option: A

What is the ideal mechanical advantage of a single fixed pulley? Can it be used as a force multiplier?

physics machines levers and pulleys pulley pulleys

  1. $1.5$, yes

  2. $1.5$, No

  3. $1$, yes

  4. $1$, No

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Correct Option: D
Explanation:

A single fixed pulley has an ideal mechanical advantage of 1 since the effort force is equal to the load force.
No, it cannot be used as a force multiplier, instead, it is used to change the direction of force applied.

$1000$ N force is required to lift a hook and $10000$ N force is requires to lift a load slowly. Find power required to lift hook with load with speed $v = 0.5 m/sec$

physics machines levers and pulleys pulley pulleys

  1. $5kw$

  2. $5.5kw$

  3. $1.5kw$

  4. $4.5kw$

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Correct Option: B
Explanation:

$P=F.V=(1000+1000)0.5$
$=\dfrac{11000}{2}=5500=5.5kw$

The machine used to separate the massive particles and light particles from a mixture is

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

  1. At wood machine

  2. Centrifugation

  3. Filter paper

  4. Separating funnel

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Correct Option: B
Explanation:

Centrifugation is the process of separating suspended particles from a liquid by rotating the liquid at a high speed. The mixture is taken in a closed bottle and rotated at a high speed. The heavy particles settle at the bottom while light particles remain behind. This method is used to separate cream from milk

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 force

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

  4. all of the above

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Correct Option: D

A pulley system has a velocity ratio $3$ and an efficiency of $80\%$. Calculate the effort required to raise a load of $300N$.

physics machines levers and pulleys pulley pulleys

  1. $125 N$

  2. $300 N$

  3. $150 N$

  4. $225 N$

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Correct Option: A
Explanation:
$Velocity\ Ratio = 3$

$Efficiency = 80/100$

$Mechanical \ Advantage = efficiency \times Velocity\  ratio$

$\Rightarrow \dfrac{80}{100} \times 3 $

$\Rightarrow 2.4$


$M.A = \dfrac{load}{effort}$

$2.4 = \dfrac{300 N}{Effort}$

$\Rightarrow Effort = \dfrac{300 N}{2.4} = 125N$

In a single fixed pulley, if the effort moves by a distance $x$ downwards, by what height is the load raised upwards?

physics machines levers and pulleys pulley pulleys

  1. $2x$

  2. $x$

  3. $x/2$

  4. $x/g$

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Correct Option: B
Explanation:

We know that for a single fixed pulley, Distance moved by effort is equal to the distance moved by load.
$ Distance\; moved \;by\; effort = x$
$\therefore Distance \;moved \;by \;load = x$

A car steering is an example of :

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

  1. first order lever

  2. second order lever

  3. complex machine

  4. wheel-and-axle

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Correct Option: D

A pulley system has a velocity ratio $3$ and an efficiency of $80\%$. Calculate the mechanical advantage of the system.

physics machines levers and pulleys pulley pulleys

  1. $2.0$

  2. $3.0$

  3. $2.4$

  4. $1.4$

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Correct Option: C
Explanation:

$Velocity\ Ratio = 3$


$Efficiency = 80/100$

$Mechanical \ Advantage = efficiency \times Velocity\  ratio$

$\Rightarrow \dfrac{80}{100} \times 3 $

$\Rightarrow 2.4$