Chapter 4 – Turning Effect of Forces

Chapter 4 – Turning Effect of Forces

Chapter 4 – Turning Effect of Forces

Chapter 4 – Turning Effect of Forces

Chapter 4 – Turning Effect of Forces

 

A force of 150 N can loosen a nut when applied at the end of a spanner 10cm long.

F          =          150 N

L          =          10 cm =          0.1 m

So

t          =          F x L

t          =          150 x 0.1

t          =          15 Nm

What should be the length of the spanner to loosen the same nut with a 60 N force?

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Ans:    As

t          =          F x L

15        =          60 x L

L          =         15 / 60

L          =          0.25 m

L          =          25 cm

How much force would be sufficient to loosen it with a 6 cm long spanner?

Ans:    As

L          =          6 cm =          0.06 m

t          =          F x L

15        =          F x 0.06 m

L          =    15 / 0.06

L          =          250 N

Can a smart child play with a fat child on the see-saw? Explain how?

Ans:    Yes, Fat child can play with smart child by adjusting the moment arm.

Two children are sitting on the see-saw, such that they can not swing. What is the net torque in this situation?

Ans:    In this case, net torque such that they can swing. In this case, net torque would be zero because clockwise torque is equal to Anticlockwise torque.

A ladder leaning at a wall as shown in figure 4.31 is in equilibrium. How?

Ans:    Ladder is in equilibrium because it satisfies second condition of equilibrium.

The weight of the ladder in figure 4.31 produces an anticlockwise torque. The wall pushes the ladder at its top end thus produces a clockwise torque. Does the ladder satisfy second condition for equilibrium?

Ans:    Yes, it satisfies second condition of equilibrium because both torques are equal in magnitude but opposite in direction.

Does the speed of a ceiling fan go on increasing all the time?

Ans:    Speed of ceiling fan does not increase all the times. At acquiring maximum speed it moves with uniform speed.  

Does the fan satisfy second condition for equilibrium when rotation with uniform speed?

Ans:    No, it does not satisfy the second condition of equilibrium. Because it neither in the state of rest nor moving with uniform velocity.

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This Post Has 39 Comments

  1. Razzaq

    It realy help me

  2. asim saeed

    wow

    1. Heyah

      Excelent really helped me alot

  3. Muhammad ismail

    Sir extra Short questions ni mill rhy

  4. Naveed Javed

    Sir extra Short questions ni mill rhy

    1. Nawas

      Did you find extra short questions? If yes kindly share it

  5. ...

    Mistake in last problem..

    1. Author

      ok, we’ll correct it

  6. Laiba Ameer

    The first McQ is wrongly answered.
    Couple

    1. Author

      ok, we’ll correct it

  7. Ali

    The first mcq of exercise is wrong. The correct answer is COUPLE. Kindly, correct it.

    1. Author

      ok, we’ll correct it

  8. Suleman

    Mistake in first MCQ

  9. Suleman

    This website really helped me

  10. HAFSA AMIR

    TWO PEOPLE ALRIDY SAY THIS WHY ARE YOU REPATIN THE SAME MISTAKE

    1. Hashim

      Acha

  11. EMAAN

    Sir Kindly Correct the First MCQ it is wrong

    1. Author

      OK, we’ll correct it.

  12. Arfa

    This website is amazing

  13. Muhammad Usman

    In questions, MCQs no. 1 is incorrect. The correct answer is COUPLE

    1. Author

      OK, we’ll correct it.

  14. Anam

    this website is nice

  15. Haniyeh

    Sir in numerical 10, the length 2 is 1cm, you have wrote 50. Kindly check it up.

    1. Soon hak

      It’s really helpful
      Thank you so much

  16. Aqsachaudhary2002

    Dear sir the answer of 1st numerical was wrong please check again

    1. Author

      ok, we’ll check it.

  17. Rayyan

    the 4.1 First MCQ is incorrect,its a couple,not a torrque

    1. Organizer

      ok, we’ll check it.

  18. Ubaid

    Question KY answer likhny my taklif Hoti hy go Q no 2 likh dyty ho

    1. Erina

      😂wahi toh itni mushkil hoti

  19. Muhammad Ahmed

    Ninth class physics chapter no.4 numerical no.10 solution is incorrect

    1. Author

      Okay, we’ll check it.

  20. *Areesha Mirza*

    It’s really really soo helpful for me…. Thx slot for this website ☺…& the first Mcq is wrong but my bro told me this…. So it is not a major problem… 🤗

  21. Hanan

    Sir physics class 9 ch 4 mcqs no 1 is incorrect. Correct answer is ( couple ). Please correct it. Thank you so much for your hard work. May Allah bless you more.

    1. Organizer

      ok, we’ll check it.

  22. Azaan

    In the question of 4.2 ..Find the perpendicular components..Not the rectangular. Please correct this mistake

    1. Organizer

      ok, we’ll check it.

  23. Dawood Nasir

    The first mcqs is wrongly answered .

  24. Shumaila

    Kindly download option open kr dy

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