Tag: machines

Quizzes (3) Questions (32)

Questions Related to machines

Multiple choice physics machines levers and pulleys pulley pulleys

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 

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice physics machines levers and pulleys pulley pulleys

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

  1. $1.5$, yes

  2. $1.5$, No

  3. $1$, yes

  4. $1$, No
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

Multiple choice physics machines levers and pulleys pulley pulleys

$1000$ 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 $v = 0.5 m/sec$

  1. $5kw$

  2. $5.5kw$

  3. $1.5kw$

  4. $4.5kw$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

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

Multiple choice physics machines levers and pulleys pulley pulleys

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

  1. $125 N$

  2. $300 N$

  3. $150 N$

  4. $225 N$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
$Velocity\ Ratio = 3$

$Efficiency = 80/100$

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

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

$\Rightarrow 2.4$


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

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

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

Multiple choice physics machines levers and pulleys pulley pulleys

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

  1. $2x$

  2. $x$

  3. $x/2$

  4. $x/g$
Reveal answer Fill a bubble to check yourself
B Correct answer
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$
$\therefore Distance \;moved \;by \;load = x$

Multiple choice physics machines levers and pulleys pulley pulleys

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

  1. $2.0$

  2. $3.0$

  3. $2.4$

  4. $1.4$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$Velocity\ Ratio = 3$


$Efficiency = 80/100$

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

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

$\Rightarrow 2.4$

Multiple choice physics machines levers and pulleys pulley pulleys

In a fixed pulley 

  1. load and effort are equal

  2. load is greater than effort

  3. load is less than effort

  4. both have no relation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a single fixed pulley, the effort applied equals the load being lifted, as the mechanical advantage is 1.

Multiple choice physics machines levers and pulleys pulley pulleys

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 $60\%$

  1. $250 kgf$

  2. $260 kgf$

  3. $350 kgf$

  4. $360 kgf$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

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

Multiple choice physics machines levers and pulleys pulley pulleys

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

  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
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A fixed pulley does not reduce the weight or add force; it simply changes the direction of the force, allowing the user to use their body weight to pull down instead of lifting up.