Question

A block of mass 50 kg is moving with speed of 10 m/s on a rough horizontal surface (friction coefficient of 0.3). Find the kinetic friction acting on the object.

• A. 500 N
• B. 150 N
• C. 167 N
• D. 16 N

Answer 1

The Correct Option is B

To find the kinetic friction acting on a block moving on a rough horizontal surface, we can use the formula for kinetic friction:

\(\text{Friction force, } f_k = \mu_k \cdot N\)

where:

• \(\mu_k\) is the coefficient of kinetic friction.
• \(N\) is the normal force acting on the block.

Since the surface is horizontal, the normal force \(N\) is equal to the weight of the block:

\(N = m \cdot g\)

where:

• \(m\) is the mass of the block (50 kg).
• \(g\) is the acceleration due to gravity (9.8 m/s\(^2\)).

Substituting the values, we get:

\(N = 50 \, \text{kg} \times 9.8 \, \text{m/s}^2 = 490 \, \text{N}\)

Now, we can calculate the kinetic friction:

\(f_k = \mu_k \cdot N = 0.3 \times 490 \, \text{N} = 147 \, \text{N}\)

Following the options provided, the closest value to 147 N considering rounding could be:

• 150 \, \text{N}

Thus, the correct answer is 150 N.