Question

A body of mass 10 kg is kept on a horizontal surface. The coefficient of kinetic friction between the body and the surface is 0.5. A horizontal force of 60N is applied on the body. The resulting acceleration of the body is about

• A. 5 ms^-2
• B. 6 ms^-2
• C. zero
• D. 1 ms^-2

Answer 1

The Correct Option is D

Given: 

• Mass of the body, \( m = 10 \) kg
• Coefficient of kinetic friction, \( \mu_k = 0.5 \)
• Applied horizontal force, \( F = 60 \) N
• Acceleration due to gravity, \( g = 9.8 \) m/s²

Step 1: Calculate the Frictional Force

The kinetic friction force is given by:

\[ f_k = \mu_k \times N \]

Since the normal force \( N \) is equal to the weight of the body:

\[ N = mg = 10 \times 9.8 = 98 \text{ N} \]

\[ f_k = 0.5 \times 98 = 49 \text{ N} \]

Step 2: Apply Newton's Second Law

The net force acting on the body is:

\[ F_{ ext{net}} = F - f_k \]

\[ F_{ ext{net}} = 60 - 49 = 11 \text{ N} \]

Now, using Newton's second law:

\[ F = ma \]

\[ 11 = 10a \]

\[ a = \frac{11}{10} = 1.1 \approx 1 \text{ m/s}^2 \]

Answer: The acceleration of the body is about 1 m/s² (Option D).