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Grade 12th passMechanics

A block of mass 10 Kg is placed on a rough inclined surface as shown in figure the acceleration of the block will be

Question image for A block of mass 10 Kg is placed on a rough inclin
Profile image of Sameer
7 Years agoGrade 12th pass
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1 Answer

Profile image of Rituraj Tiwari
5 Years ago

To determine the acceleration of a block with a mass of 10 kg placed on a rough inclined surface, we need to analyze the forces acting on the block. The key factors to consider include the gravitational force, the normal force, the frictional force, and the angle of the incline. Here’s how we can break it down step by step.

Understanding the Forces Involved

When the block is on an inclined plane, gravity pulls it downward. This gravitational force can be broken into two components: one acting parallel to the incline and another acting perpendicular to it.

1. Gravitational Force Components

The weight of the block (W) is given by the formula:

W = m × g

Where:

  • m is the mass (10 kg)
  • g is the acceleration due to gravity (approximately 9.81 m/s²)

So, the weight of the block is:

W = 10 kg × 9.81 m/s² = 98.1 N

2. Components of Weight

The weight can be split into two components based on the angle of incline (θ):

  • The component parallel to the incline: W_parallel = W × sin(θ)
  • The component perpendicular to the incline: W_perpendicular = W × cos(θ)

3. Normal Force

The normal force (N) acts perpendicular to the surface and is equal to the perpendicular component of the weight when there’s no vertical motion:

N = W_perpendicular = W × cos(θ)

4. Frictional Force

If the surface is rough, friction will oppose the motion of the block. The frictional force (F_friction) can be calculated using:

F_friction = μ × N

Where:

  • μ is the coefficient of friction.

Setting Up the Equation of Motion

Using Newton's second law, the net force acting on the block along the incline can be expressed as:

F_net = W_parallel - F_friction

Hence, we get:

m × a = W_parallel - F_friction

Where a is the acceleration of the block. Rearranging gives:

a = (W_parallel - F_friction) / m

Calculating Acceleration

Let’s say the angle of inclination is θ degrees and the coefficient of friction is μ. Plugging in the values we discussed:

  • W_parallel = 98.1 N × sin(θ)
  • N = 98.1 N × cos(θ)
  • F_friction = μ × (98.1 N × cos(θ))

Finally, substitute these into the acceleration equation:

a = (98.1 N × sin(θ) - μ × (98.1 N × cos(θ))) / 10 kg

Example Calculation

For instance, if the incline angle θ is 30 degrees and the coefficient of friction μ is 0.2, we can calculate:

  • W_parallel = 98.1 N × sin(30°) = 49.05 N
  • N = 98.1 N × cos(30°) ≈ 84.87 N
  • F_friction = 0.2 × 84.87 N ≈ 16.97 N

Now plug these into the acceleration formula:

a = (49.05 N - 16.97 N) / 10 kg = 3.81 m/s²

Thus, the acceleration of the block down the incline would be approximately 3.81 m/s² if the conditions are as stated. Adjust the values based on your specific angle and coefficient of friction for your situation!