9394949438

[LATEST]$type=sticky$show=home$rm=0$va=0$count=4$va=0



Physics Quiz-11

Dear Readers,

If an object changes its position with respect to its surroundings with time, then it is called in motion. It is a change in the position of an object over time. Motion in a straight line is nothing but linear motion. As the name suggests, it’s in a particular straight line, thus it can be said that it uses only one dimension.


Q1. A 2 m wide truck is moving with a uniform speed v_0=8 ms^(-1) along a straight horizontal road. A pedestrian starts to cross the road with a uniform speed v when the truck is 4 m away from him. The minimum value of  v so that he can cross the road safely is
  •  2.62 ms^(-1)
  •  4.6 ms^(-1)
  •  3.57 ms^(-1)
  • 1.414 ms^(-1)
Solution
Let the man start crossing the road at an angle θ with the roadside. For safe crossing, the condition is that the man must cross the road by the time the truck describes the distance (4+2 cot⁡θ)


So, (4+2 cot⁡θ)/8=(2/sin⁡θ)/v  or v=8/(2 sin⁡〖θ+cos⁡θ 〗 )
For minimum v,dv/dθ=0
or (-8(2 cos⁡〖θ-sin⁡θ 〗))/(2 sin⁡〖θ+cos⁡θ 〗 )^2 =0 or 2 cos⁡〖θ-sin⁡〖θ=0〗 〗
or tan⁡〖θ=2〗, so sin⁡〖θ=2/√5〗,cos⁡〖θ=1/√5〗
v_min=8/(2(2/√5)+1/√5)=8/√5=3.57 ms^(-1)

Q2.A person moves 30 m north and then 20 m towards east and finally 30√2 m in south-west direction. The displacement of the person from the origin will be
  •  10 m along north
  •  10 m along south
  •  10 m along west
  •  Zero
Solution
AB=30 m,BC=20 m,CD=30 √2  
DBCE is isosceles (Fig), so
BE=BC=20 m
AE=AB-BE=30-20=10 m
EC=20 √2  m
ED=CD-EC=30 √2-20√2=10√2 m
DADE is isosceles, so AD=AE=10 m









Q3. A body is projected upwards with a velocity u. It passes through a certain point above the ground after t_1. The time after which the body passes through the same point during the return journey is
  •  (u/g-t_1^2 )
  •  2(u/g-t_1 )
  • 3(u^2/g-t_1 )
  • 3(u^2/g^2 -t_1 )
Solution
Suppose v be the velocity attained by the body after time t_1. Then v=u-gt_1 (i)
Let the body reach the same point at time t_2. Now velocity will be downwards with same magnitude v, then –v=u-gt_2   …(ii)
(i)-(ii) ⇒2v=g(t_2-t_1)
or t_2-t_1=2v/g=2/g  (u-gt_1 )=2(u/g-t_1 )

Q4. The velocity acquired by a body moving with uniform acceleration is 30 ms^(-1) in 2 s and 60 ms^(-1) in 2 s. The initial velocity is
  •  Zero
  • 2 ms^(-1)
  •  3 ms^(-1)
  •  10 ms^(-1)
Solution
30=u+a×2,60=u+a×4
Solve to get u=0

Q5.The acceleration will be positive in







  •  (I) and (III)
  •  (I) and (IV)
  •  (II) and (IV)
  •  None of these
Solution
In (I), slope is negative and its magnitude is decreasing with time. It means slope is increasing numerically. So velocity is increasing towards right, and so acceleration is positive.
In (IV), slope is positive and its magnitude is increasing with time. So velocity is increasing towards right, and so acceleration is positive.

Q6.  

      The angle between velocity and acceleration during retarded motion is

  •  180°
  •  40°
  •  45°
  •  0°
Solution
During retarded motion, acceleration and velocity are in opposite directions

Q7.
Two trains A and B, 100 m and 60 m long, are moving in opposite directions on parallel tracks. The velocity of the shorter train is 3 times that of the longer one. If the trains take 4 s to cross each other, the velocities of the trains are
  • V_A=10 ms^(-1),V_B=30 ms^(-1)
  • V_A=2.5 ms^(-1),V_B=7.5 ms^(-1)
  •  V_A=20 ms^(-1),V_B=60 ms^(-1)
  •  V_A=5 ms^(-1),V_B=15 ms^(-1)
Solution
3V_A=V_B,S_rel=n_rel t ⇒100+60=(V_A+V_B)×4
Solve to get V_A=10 ms^(-1) and V_B=30 ms^(-1)

Q8. A body covers one-third of the distance with a velocity v_1, the second one-third of the distance with a velocity v_2, and the remaining distance with a velocity v_3. The average velocity is
  •  (v_1+v_2+v_3)/3
  • (3v_1 v_2 v_3)/(v_1 v_2+v_2 v_3+v_3 v_1 )
  • (v_1 v_2+v_2 v_3+v_3 v_1)/3
  •  (v_1 v_2 v_3)/3
Solution
t_1=(S/3)/v_1 ,t_2=(S/3)/v_2 ,t_3  (S/3)/v_3 
v_av=S/(t_1+t_2+t_3 )=(3v_1 v_2 v_3)/(v_1 v_2+v_2 v_3+v_3 v_1 )

Q9.

    A ball is thrown upwards with speed v from the top of a tower and it reaches the ground with speed 3v. What is the height of the tower?


  •  v^2/g
  • (2v^2)/g
  •  (4v^2)/g
  •  (8v^2)/g
    Solution
    According to the third equation of motion,
    v^2-u^2=2as
    Given v=3v,u=v and a=g
    or (3v)^2-v^2=2gs or s=(4v^2)/g
Q10. Two cars A and B are travelling in the same direction with velocities V_A and V_B  (V_A>V_B). When the car A is at a distance s behind car B, the driver of the car A applies the brakes producing a uniform retardation a; there will be no collision when
  •  s<(V_A-V_B )^2/2a
  • s=(V_A-V_B )^2/2a
  •  s≥(V_A-V_B )^2/2a
  • s≤(V_A-V_B )^2/2a
Solution
For no collision, the speed of car A should be reduced to v_B before the cars meet, i.e., final relative velocity of car A with respect to car B is zero, i.e., V_r=0
Here u_r=initial relative velocity =V_A-V_B
Relative acceleration =a_r=-a-0=-a
Let relative displacement =s_r
Then using the equation, v_r^2=u_r^2+2a_r s_r
0^2=(V_A-V_B )^2-2as_r or s_r=(V_A-V_B )^2/2a
For no collision, s_r≤s i.e., (V_A-V_B )^2/2a≤s



author image

Written by: AUTHORNAME

AUTHORDESCRIPTION

Want to know more

Please fill in the details below:

INNER POST ADS

Latest IITJEE Articles$type=three$c=3$author=hide$comment=hide$rm=hide$date=hide$snippet=hide

Latest NEET Articles$type=three$c=3$author=hide$comment=hide$rm=hide$date=hide$snippet=hide

Name

Admissions,1,Alternating Current,60,AP EAMCET 2020,1,Basic Maths,2,BCECE 2020,1,best books for iit jee,2,best coaching institute for iit,1,best coaching institute for iit jee preparation,1,best iit jee coaching delhi,1,best iit jee coaching in delhi,2,best study material for iit jee,4,BITSAT Registration 2020,1,Blog,62,books for jee preparation,1,books recommended by iit toppers,3,Capacitance,3,CBSE,1,CBSE accounts exam,1,CBSE boards,1,CBSE NEET,9,cbse neet 2019,3,CBSE NEET 2020,1,cbse neet nic,1,Centre of Mass,2,Chemistry,58,Class 12 Physics,15,coaching for jee advanced,1,coaching institute for iit jee,2,Collision,2,COMEDK UGET 2020 Application Form,1,COMEDK UGET 2020 Exam Form,1,COMEDK UGET news,1,CUCET 2020,2,Current Electricity,4,CVR college,1,Digestion and Absorption Notes PDF,1,Electromagnetic Induction,3,Electronics,1,Electrostatics,3,Energy,1,Engineering & Medical,1,Fluid Mechanics,4,Gravitation,2,GUJCET 2020 Application Form,1,Heat,4,iit admission,1,iit advanced,1,iit coaching centre,3,iit coaching centre in delhi,2,iit coaching classes,2,iit coaching in delhi,1,iit coaching institute in delhi,1,iit entrance exam,1,iit entrance exam syllabus,2,iit exam pattern,2,iit jee,5,iit jee 2019,3,iit jee advanced,2,iit jee books,3,iit jee coaching,2,iit jee exam,3,iit jee exam 2019,1,iit jee exam pattern,3,iit jee institute,1,iit jee main 2019,2,iit jee mains,3,iit jee mains syllabus,2,iit jee material,1,iit jee online test,3,iit jee practice test,3,iit jee preparation,6,iit jee preparation in delhi,2,iit jee preparation time,1,iit jee preparation tips by toppers,2,iit jee question paper,1,iit jee study material,3,iit jee study materials,2,iit jee syllabus,2,iit jee syllabus 2019,2,iit jee test,3,iit preparation,2,iit preparation books,5,iit preparation time table,2,iit preparation tips,2,iit syllabus,2,iit test series,3,IITJEE,100,Important Biology Notes for NEET Preparation,1,IPU CET,1,JEE Advanced,83,jee advanced exam,2,jee advanced exam pattern,1,jee advanced paper,1,JEE Books,1,JEE Coaching Delhi,3,jee exam,3,jee exam 2019,6,JEE Exam Pattern,2,jee exam pattern 2019,1,jee exam preparation,1,JEE Main,85,jee main 2019,4,JEE Main 2020,1,JEE Main 2020 Application Form,2,JEE Main 2020 news,2,JEE Main 2020 Official Answer Key,1,JEE Main 2020 Registration,1,JEE Main 2020 Score,1,JEE Main application form,1,jee main coaching,1,JEE Main eligibility criteria,3,jee main exam,1,jee main exam 2019,3,jee main online question paper,1,jee main online test,3,JEE Main Paper-2 Result,1,jee main registration,2,jee main syllabus,2,JEE mains 2020,1,jee mains question bank,1,jee mains test papers,3,JEE Mock Test,2,jee notes,1,jee past papers,1,JEE Preparation,2,jee preparation in delhi,1,jee preparation material,4,JEE Study Material,1,jee syllabus,6,JEE Syllabus Chemistry,1,JEE Syllabus Maths,1,JEE Syllabus Physics,1,jee test series,3,KCET - 2020,1,Kinematics,1,Latest article,5,Latest Articles,61,Latest News,34,latest news about neet exam,1,Laws of Motion,2,Magnetic Effect of Current,3,Magnetism,3,MHT CET 2020,2,MHT CET 2020 exam schedule,1,Modern Physics,1,NCERT Solutions,15,neet,3,neet 2019,1,neet 2019 eligibility criteria,1,neet 2019 exam date,2,neet 2019 test series,2,NEET 2020,2,NEET 2020 Application Form,1,NEET 2020 Eligibility Criteria,1,NEET 2020 Registration,1,neet application form,1,neet application form 2019 last date,1,Neet Biology Syllabus,1,Neet Books,3,neet eligibility criteria,3,neet exam 2019,7,neet exam application,1,neet exam date,1,neet exam details,1,neet exam pattern,6,neet exam pattern 2019,2,neet examination,1,neet mock test 2019,1,Neet Notes,3,Neet Online Application Form,3,neet online test,2,neet past papers,1,neet physics syllabus,1,neet practice test,2,NEET preparation books,1,neet qualification marks,1,NEET question paper 2019,1,neet question papers,1,neet registration,1,Neet Study Material,3,neet syllabus,6,neet syllabus 2019,5,NEET Syllabus 2020,1,neet syllabus chemistry,1,neet syllabus for biology,1,neet syllabus for physics,1,neet test series,1,neet ug 2019,2,news,5,online study material for iit jee,1,Optical Instruments,1,Physics,110,physics books for iit jee,1,Power,1,Practical Physics,1,Quiz,5,Ray Optics,1,Rotational Motion,3,SHM,3,Simple Harmonic Motion,3,study materials for iit jee,1,Study Notes,110,study notes for iit jee,1,Thermodynamics,4,TS EAMCET Notification,2,Units and Dimensions,1,UPSEE 2020,1,UPSEE 2020 Application Form,2,UPSEE EXAM,1,Vectors,2,VITEE Application form,1,Wave Motion,3,Wave Optics,1,WBJEE 2020 Admit Card,1,WBJEE 2020 Answer Key,1,Work,1,
ltr
item
BEST NEET COACHING CENTER | BEST IIT JEE COACHING INSTITUTE | BEST NEET & IIT JEE COACHING
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdTkD1xPmS-I70VrXTbcq66geR-kNqW-5l_n7UhWd0HvrtMKxVSkGBDdi44Nut-6rRWJYXYkgZYFuCkY0vyHZex7MJgiND3yHwKJa_jaHBPYzhbekUwpsr6mMZpxDlbpL6m20vrdbWSVI/w365-h193/QUIZ+BACK.png
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdTkD1xPmS-I70VrXTbcq66geR-kNqW-5l_n7UhWd0HvrtMKxVSkGBDdi44Nut-6rRWJYXYkgZYFuCkY0vyHZex7MJgiND3yHwKJa_jaHBPYzhbekUwpsr6mMZpxDlbpL6m20vrdbWSVI/s72-w365-c-h193/QUIZ+BACK.png
BEST NEET COACHING CENTER | BEST IIT JEE COACHING INSTITUTE | BEST NEET & IIT JEE COACHING
https://www.cleariitmedical.com/2021/07/physics-quiz-11-dear-readers-if-object.html
https://www.cleariitmedical.com/
https://www.cleariitmedical.com/
https://www.cleariitmedical.com/2021/07/physics-quiz-11-dear-readers-if-object.html
true
7783647550433378923
UTF-8
Loaded All Posts Not found any posts VIEW ALL Readmore Reply Cancel reply Delete By Home PAGES POSTS View All RECOMMENDED FOR YOU LABEL ARCHIVE SEARCH ALL POSTS Not found any post match with your request Back Home Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sun Mon Tue Wed Thu Fri Sat January February March April May June July August September October November December Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec just now 1 minute ago $$1$$ minutes ago 1 hour ago $$1$$ hours ago Yesterday $$1$$ days ago $$1$$ weeks ago more than 5 weeks ago Followers Follow THIS CONTENT IS PREMIUM Please share to unlock Copy All Code Select All Code All codes were copied to your clipboard Can not copy the codes / texts, please press [CTRL]+[C] (or CMD+C with Mac) to copy

STAY CONNECTED