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12th Grade > Physics


Circular Kinematics

Total Questions : 41 | Page 3 of 5 pages
Question 21. A balloon starts rising from the surface of the Earth. The ascension rate is constant and equal to vo. Due to the wind the balloon gathers the horizontal velocity component vx=ay, where a is a constant and y is the height of ascent. Find the total, tangential, and normal accelerations of the balloon.
  1.    ar=av0;at=av0√1+(ayv0)2;aN=av0
  2.    ar=av0;at=av0;aN=0
  3.    ar=av0;at=a2y√1+a2y2v20;aN=av0 ⎷(1+a2y2v20)
  4.    ar=a2y√1+a2y2v20;at=av0;aN=av0
 Discuss Question
Answer: Option C. -> ar=av0;at=a2y√1+a2y2v20;aN=av0 ⎷(1+a2y2v20)
The path of the balloon will look something like this
A Balloon Starts Rising From The Surface Of The Earth. The A...
After t sec ballon would have gone a height of v0tthen at that very instance the balloon's vx will be
vtangentical is actually the resultant velocity
Now we know a2t+a2N=a2r
Question 22. A hollow vertical cylinder of radius R and height h has smooth internal surface. A small particle is placed in contact with the inner side of the upper rim at a point P. It is given a horizontal speed vo tangential to rim. It leaves the lower rim at point Q, vertically below P. The number of revolutions made by the particle will
  1.    h2πR
  2.    v0√2gh
  3.    2πRh
  4.    v02πR(√2hg)
 Discuss Question
Answer: Option D. -> v02πR(√2hg)
since the body has no initial velocity in the vertical direction.
A Hollow Vertical Cylinder Of Radius R And Height H Has Smoo...
az=-g, vertical displacement z=-h.
T=2hg time taken to reach the bottom
let,t be the time taken to complete one revolution.
Then t=2πRv0
number of revolution=Tt=2hg2πRv0=v02πR2hg
Question 23. Find the maximum velocity for skidding for a car moved on a circular track of radius 100 m. The coefficient of friction between the road and tyre is 0.2
  1.    0.14 m/s
  2.    140 m/s
  3.    1.4 km/s
  4.    14 m/s
 Discuss Question
Answer: Option D. -> 14 m/s
Question 24. A point P moves in counter-clockwise direction on a circular path as shown in the figure. The movement of 'P' is such that it sweeps out a length s=t3+5, where s is in meters and t is in seconds. The radius of the path is 20 m. The acceleration of 'P' when t = 2 s is nearly
A Point P Moves In Counter-clockwise Direction On A Circular...
  1.    13 m/s2
  2.    12 m/s2
  3.    7.2 m/s2
  4.    14 m/s2
 Discuss Question
Answer: Option D. -> 14 m/s2
Speed,v=dsdt=3t2 and rate of change of speed =dvdt=6t
tangential acceleration at t=2S,at = 6 × 2=12m/s2
centripetal acceleration,
net acceleration=a2t+a2i14m/s2
Question 25. Which is these is a possible direction of acceleration for a point on a car that is going on a circular track and is speeding up?
Which Is These Is A Possible Direction Of Acceleration For A...
  1.    a
  2.    b
  3.    c
  4.    d
 Discuss Question
Answer: Option D. -> d
The net acceleration is always directed between radially inward and tangential direction.
Question 26. A particle of mass M moves with constant speed along a circular path of radius r under the action of a force F.  Its speed is
  1.    √rFm
  2.    √Fr
  3.    √Fmr
  4.    √Fmr
 Discuss Question
Answer: Option A. -> √rFm
Question 27. A body takes the following path and moves with constant speed. If aA and aB are the magnitude of its radial acceleration at A and B.
A Body Takes The Following Path And Moves With Constant Spee...
  1.    aA=aB
  2.    aA
  3.    aA>aB
  4.    none of these
 Discuss Question
Answer: Option C. -> aA>aB
The radius of curvature is the radius of the osculating circle at that point of the curve.
A Body Takes The Following Path And Moves With Constant Spee...
We can clearly see that RA<RB
v2RA>v2RB (as v is the speed and is constant)
Question 28. The speed of the truck is 40 m s-1, after 10 seconds its speed decreases to 20 m s-1, its acceleration is
  1.    -1m/s2
  2.    -2m/s2
  3.    -4m/s2
  4.    -5m/s2
 Discuss Question
Answer: Option B. -> -2m/s2
Question 29. Which of the following is NOT a unit for acceleration?
  1.    m/s2
  2.    cm/s2
  3.    km/hr
  4.    km/hr2
 Discuss Question
Answer: Option C. -> km/hr
Question 30. Calculate the speed of a sprinter who ran 200 meters in 20 seconds
  1.    10m/s
  2.    10km/s
  3.    10m/hr
  4.    10km/hr
 Discuss Question
Answer: Option A. -> 10m/s

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