Kinematics
- If the magnitude of sum of two vectors is equal to the magnitude of difference of the two vectors, the angle between these vectors is : Answer: 2. 90^° Key idea: |vec A+vec B|²=A²+B²+2ABcosθ and |vec A-vec B|²=A²+B²-2ABcosθ . Setting them equal gives 4ABcosθ=0 , so cosθ=0 and... 1
- A particle of mass 10 g moves along a circle of radius 6.4 cm with a constant tangential acceleration. What is the magnitude of this acceleration if the kinetic energy of the particle becomes equal to 8×10^-4 J by the end of the second revolution aft… Answer: 1. 0.1\ m/s² Key idea: constant tangential acceleration a gives v²=2as along the arc. 1/2mv²=8×10⁻⁴⇒ v²=dfrac2×8×10⁻⁴0.01=0.16 m ² /... 1
- A particle moves so that its position vector is given by r = ω t x + ω t y. Where ω is a constant. Which of the following is true ? Answer: 3. Velocity is perpendicular to r and acceleration is directed towards the origin. Key idea: this is uniform circular motion of unit... 1