Work, Energy & Power · JEE Main previous year questions

2018 3 questions

1. Q332018 · 16 Apr 2018 · Shift 1

   A body of mass m starts moving from rest along x-axis so that its velocity varies as $v=a\sqrt{s}$ where a is a constant and s is the distance covered by the body. The total work done by all the forces acting on the body in the first t seconds after the start of the motion is :

   1. A.$\frac{1}{8}m{a}^4{t}^2$
   2. B.$8m{a}^4{t}^2$
   3. C.$4m{a}^4{t}^2$
   4. D.$\frac{1}{4}m{a}^4{t}^2$
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   Answer: A

2. Q352018 · 16 Apr 2018 · Shift 1

   An oscillator of mass M is at rest in its equilibrium position in a potential $\text{V}=\frac{1}{2}\text{k}(\text{x}-\text{X}{)}^2$. A particle of mass m comes from right with speed u and collides completely inelastically with M and sticks to it. This process repeats every time the oscillator crosses its equilibrium position. The amplitude of oscillations after 13 collisions is : (M = 10, m = 5, u = 1, k = 1)

   1. A.$\frac{1}{\sqrt{3}}$
   2. B.$\frac{1}{2}$
   3. C.$\frac{2}{3}$
   4. D.$\sqrt{\frac{3}{5}}$
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   Answer: A

3. Q342018 · 8 Apr 2018 · Shift 1

   In a collinear collision, a particle with an initial speed $v_0$ strikes a stationary particle of the same mass. If the final total kinetic energy is 50% greater than the original kinetic energy, the magnitude of the relative velocity between the two particles, after collision, is :

   1. A.$\frac{v_0}{\sqrt{2}}$
   2. B.$\frac{v_0}{4}$
   3. C.$\sqrt{2}{v}_0$
   4. D.$\frac{v_0}{2}$
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   Answer: C