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Concepts Of Physics MCQ Edition [Volume 1]
Exam
Concepts Of Physics MCQ Edition [Volume 1]
Subject
Physics
Chapter
Work and Energy

Concepts Of Physics MCQ Edition [Volume 1] · Physics · Work and Energy

A small block of mass 200 g is situated at the top of a...

A small block of mass 200 g200 \text{ g} is situated at the top of a frictionless incline which is 10 m10 \text{ m} long and 3.2 m3.2 \text{ m} high. Determine the speed of the block when it reaches the ground if it falls off the incline and drops vertically to the ground. Take g=10 m/s2g = 10 \text{ m/s}^2.

Options

  1. A5.7 m/s5.7 \text{ m/s}
  2. B64.0 m/s64.0 \text{ m/s}
  3. C8.0 m/s8.0 \text{ m/s}
  4. D14.1 m/s14.1 \text{ m/s}

Correct answer

C. 8.0 m/s8.0 \text{ m/s}

Step-by-step solution

By the principle of conservation of mechanical energy, the potential energy of the block at the top is converted entirely into kinetic energy when it reaches the ground.

mgh=12mv2mgh = \dfrac{1}{2}mv^2

v=2ghv = \sqrt{2gh}

Given that the height of the incline is h=3.2 mh = 3.2 \text{ m} and g=10 m/s2g = 10 \text{ m/s}^2, we substitute these values into the equation:

v=2×10×3.2v = \sqrt{2 \times 10 \times 3.2}

v=64=8.0 m/sv = \sqrt{64} = 8.0 \text{ m/s}

The mass of the block and the length of the incline are extraneous information.
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