Tag: physics

Questions Related to physics

A pulley system of VR of 2 and efficiency of 50%. If the effort moves through a distance of 5m. Calculate the distance moved by the load.

physics simple machine common machines terms related to machines introduction to simple machines

  1. 2m

  2. 5.6m

  3. 10m

  4. 2.5m

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Correct Option: D
Explanation:

Given:  $VR=2$


From the relation $VR=\dfrac{\text{Distance moved by effort}}{\text{distance moved by load}}$


Using formula we get distance moved by the load is $2.5m$

........ is defined as the ratio of the distance moved by effort and load, in the same time interval.

physics simple machine common machines terms related to machines introduction to simple machines

  1. Velocity ratio

  2. Mechanical advantage

  3. Both

  4. None

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Correct Option: A
Explanation:

Velocity ratio = $\displaystyle \frac { Distance\quad moved\quad by\quad the\quad effort }{ Corresponding\quad distane\quad moved\quad by\quad the\quad load } $
It only depends on the design of machine and is always same for a particular machine.

Efficiency is

physics simple machine common machines terms related to machines introduction to simple machines

  1. $\displaystyle \frac { Energy\quad input }{ Energy\quad output } \times 100$

  2. $\displaystyle \frac { mechanical\quad advantage }{ velocity\quad ratio } \times 100$

  3. Both

  4. None

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Correct Option: C
Explanation:

As no machine is perfectly efficient.
So, we define efficiency as efficiency = $\displaystyle \frac { Energy\quad input }{ Energy\quad output } \times 100$
Also Efficiency = $\displaystyle \frac { mechanical\quad advantage }{ velocity\quad ratio } \times 100$
A petrol engine is about 30% efficient, a diesel engine is 40% efficient.

A machine in which displacement of load is more than the displacement of effort, will have the velocity ratio

physics simple machine common machines terms related to machines introduction to simple machines

  1. More than 1

  2. Less than 1

  3. Equal to 1

  4. All

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Correct Option: B
Explanation:

A machine in which displacement of load is more than the displacement of effort, will have the velocity ratio more than 1.

Friction has no effect on 

physics simple machine common machines terms related to machines introduction to simple machines

  1. Velocity Ratio

  2. Mechanical Advantage

  3. Efficiency

  4. All of the above

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Correct Option: A
Explanation:

Friction has effect on Mechanical Advantage and efficiency but not Voltage Ratio.

Effeciency of inclined plane

physics simple machine common machines terms related to machines introduction to simple machines

  1. Zero

  2. One

  3. Two

  4. Three

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Correct Option: B
Explanation:

$\eta=\frac{M.A}{V.R}=\frac{l}{h(l/h)}=1$
$M.A=\frac{l}{h}, V.R=\frac{l}{h}$

Mechanical advantage of an inclined plane is 

physics simple machine common machines terms related to machines introduction to simple machines

  1. Always smaller than $1$

  2. Always greater than $1$

  3. Always equal to $1$

  4. All

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Correct Option: B
Explanation:

An inclined plane is a sloping surface that behaves like a simple machine whose mechanical advantage is always greater than $1$.

Akhil has to lift a load of $800N$ onto a platform of $2m$ height. Instead, he pushes the load up a ramp $4m$ long. Find the force required to lift the load vertically up.

physics simple machine common machines terms related to machines introduction to simple machines

  1. $200N$

  2. $600N$

  3. $400N$

  4. $800N$

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Correct Option: D
Explanation:

The vertical force is the gravitational force means weight of the load. 

According to question, the weight of load is $mg=800 N$, this will be the required force to lift the load vertically.  

Mechanical advantage =________.

physics simple machine common machines terms related to machines introduction to simple machines

  1. Load $-$ effort

  2. Load $\times $ effrot

  3. Load $/$ effort

  4. None of the above

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Correct Option: C

Which of the following statements is NOT correct?

physics simple machine common machines terms related to machines introduction to simple machines

  1. In a first order lever, the fulcrum is placed between the effort and the load

  2. The mechanical advantage of a second class levers is greater than $1$ as load is situated in between to effort and fulcrum.

  3. An inclined plane in a hospital, helps pushing a wheel chair easily.

  4. A crow bar is an example of second class lever

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Correct Option: D