JEE Main · 2021 · 18 Mar 2021 · Shift 1 · Work, Power & Energy

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As shown in the figure, a particle of mass 10 kg is placed at a point A. When the particle is slightly displaced to its right, it starts moving and reaches the point

B

. The speed of the particle at

B

x m / s

.
(Take

g = 10 m / s^{2}

)
The value of 'x' to the nearest integer is ______

Answer: 10

Solution

The particle starts from rest at A, which is

10

m above the horizontal surface, and reaches B, which is

5

m above it, so it descends through

h = 10 - 5 = 5

m. The track is smooth, so mechanical energy is conserved:

\frac{1}{2} m v^{2} = m g h \Rightarrow v = 2 g h = 2 \times 10 \times 5 = 10 m/s

The speed of the particle at B is

10

m/s.

JEE Main · 2021 · 18 Mar 2021 · Shift 1 · Integer answer

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