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А как там у них? Что решают за бугром? Начинаем.

рисунокThe original text of a problem
1. As shown above, a ball of mass m, suspended on the end of a wire, is released from height h and collides elastically, when it is at its lowest point, with a block of mass 2m at rest on a frictionless surface. After the collision, the ball rises to a final height equal to ... [To read further]

  • (A) 1/9 h
  • (B) 1/8 h
  • (C) 1/3 h
  • (D) 1/2 h
  • (E) 2/3 h

2. A particle of mass m undergoes harmonic oscillaoscillation with period To. A force f proportional to the speed v of the particle, f = −bv, is introduced. If the particle continues to oscillate, the period with f acting is ...

  • (A) larger than To
  • (B) smaller than To
  • (C) independent of b
  • (D) dependent linearly on b
  • (E) constantly changing

 Offer transfer of the given problem and its decision.

3. A block of mass m sliding down an incline at constant speed is initially at a height h above the ground, as shown in the figure above. The coefficoefficient of kinetic friction between the mass and the incline is μ. If the mass continues to slide down the incline at a constant speed, how much energy is dissipated by friction by the time the mass reaches the bottom of the incline?

  • (A) mgh/μ
  • (B) mgh
  • (C) μmgh/sinα
  • (D) mghsinα
  • (E) 0