Tag: physics

Questions Related to physics

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 $

$\Rightarrow 2.4$

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

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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. $360 kgf$

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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

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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. $90$

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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

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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

Which of the following is a poor conductor of electricity?

physics chemical effects of electric current does liquid conduct electricity? liquids conduct electricity do liquids conduct electricity?

  1. Distilled water

  2. Tap water

  3. Sea water

  4. Drinking water

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Correct Option: A
Explanation:

Distilled water is free of salts and is a poor conductor.