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Laws of Motion question

2021 · 26 Feb · Shift 1 · Q69
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  5. /2021 · 26 Feb · Shift 1 · Q69

Laws of Motion question

2021 · 26 Feb · Shift 1 · Q69

JEE MainPhysicsLaws of MotionNumerical+4 / −1
A boy pushes a box of mass 2 kg with a force F→=(20i^+10j^)N\overrightarrow F = \left( {20\widehat i + 10\widehat j} \right)NF=(20i+10j​)N on a frictionless surface. If the box was initially at rest, then ‾\underline{\hspace{2cm}}​ m is displacement along the x-axis after 10s.
Numerical answer
View written solutionFree

Correct answer: 500

  1. Given data
  • Mass of box: m=2 kgm = 2\,\text{kg}m=2kg
  • Applied force: F⃗=(20i^+10j^) N\vec F = (20\hat i + 10\hat j)\,\text{N}F=(20i^+10j^​)N
  • Time: t=10 st = 10\,\text{s}t=10s
  • Initial velocity: ux=0u_x = 0ux​=0
  • Surface is frictionless.

We need the displacement along the x-axis after 10 10\,10s.

  1. Find acceleration along x-axis

Using Newton's second law along the x-direction: Fx=maxF_x = ma_xFx​=max​

Here, Fx=20 NF_x = 20\,\text{N}Fx​=20N So, ax=Fxm=202=10 m/s2a_x = \frac{F_x}{m} = \frac{20}{2} = 10\,\text{m/s}^2ax​=mFx​​=220​=10m/s2

  1. Use kinematics along x-axis

Since initial velocity along x is zero, sx=uxt+12axt2s_x = u_x t + \frac{1}{2} a_x t^2sx​=ux​t+21​ax​t2

Substitute values: sx=0+12(10)(102)s_x = 0 + \frac{1}{2}(10)(10^2)sx​=0+21​(10)(102) sx=5×100=500 ms_x = 5 \times 100 = 500\,\text{m}sx​=5×100=500m

  1. Final answer

The displacement along the x-axis after 10 10\,10s is: 500\boxed{500}500​

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