A ball of mass 0.2 kg is thrown vertically upwards by applying a force by hand. If the hand moves 0.2 m which applying the force and the ball goes upto 2 m height further, find the magnitude of the force. Consider g = 10 m/s2

  • 22 N

  • 4 N

  • 20 N

  • 20 N


C.

20 N

mgh = Fs
F = 20 N

395 Views

Advertisement

Consider a two-particle system with particles having masses m1 and m2. If the first particle is pushed towards the centre of mass through a distance d, by what distance should the second particle be moved, so as to keep the centre of mass at the same position?

  • straight m subscript 1 over straight m subscript 2 straight d
  • straight m subscript 2 over straight m subscript 1 straight d
  • d

  • d


A.

straight m subscript 1 over straight m subscript 2 straight d straight m subscript 1 straight d space plus straight m subscript 2 straight x space equals space 0
straight x space equals space fraction numerator straight m subscript 1 straight d over denominator straight m subscript 2 end fraction
457 Views

Advertisement

An annular ring with inner and outer radii R1 and R2 is rolling without slipping with a uniform angular speed. The ratio of the forces experienced by the two particles situated on the inner and outer parts of the ring, F1/F2 is

  • R1/R2

  • (R1/R2)2

  • 1

  • 1


A.

R1/R2

straight F subscript 1 over straight F subscript 2 space equals space fraction numerator straight R subscript 1 straight omega squared over denominator straight R subscript 2 straight omega squared end fraction space equals straight R subscript 1 over straight R subscript 2
298 Views

A smooth block is released at rest on a 45° incline and then slides a distance d. The time taken to slide is n times as much to slide on rough incline than on a smooth incline. The coefficient of friction is

  • straight mu subscript straight k space equals space 1 minus 1 over straight n squared
  • straight mu subscript straight k space equals space square root of 1 minus 1 over straight n squared end root
  • straight mu subscript straight s space equals space 1 minus 1 over straight n squared
  • straight mu subscript straight s space equals space 1 minus 1 over straight n squared

A.

straight mu subscript straight k space equals space 1 minus 1 over straight n squared straight d space equals space 1 half fraction numerator straight g over denominator square root of 2 end fraction straight t subscript 1 superscript 2
straight d equals space 1 half fraction numerator straight g over denominator square root of 2 end fraction left parenthesis 1 minus straight mu subscript straight k right parenthesis straight t subscript 2 superscript 2
fraction numerator straight t subscript 2 superscript 2 over denominator straight t subscript 1 superscript 2 end fraction space equals space straight n squared space equals fraction numerator 1 over denominator 1 minus straight mu subscript straight k end fraction
288 Views

The upper half of an inclined plane with inclination φ is perfectly smooth while the lower half is rough. A body starting from rest at the top will again come to rest at the bottom if the coefficient of friction for the lower half is given by

  • 2sinφ

  • 2cosφ

  • 2tanφ
  • 2tanφ

C.

2tanφ
181 Views

Advertisement