Question

A wooden block of mass 10 kg is moving with an acceleration of 3ms on a rough floor. If the coefficient of friction is 0.3, then the applied force on it is (g=10ms)

• A. 10 N
• B. 30 N
• C. 80 N
• D. 60 N
• E. 65 N

Answer 1

The Correct Option is C

We are given the following information:

• Mass of the block (m) = 10 kg
• Acceleration (a) = 3 m/s²
• Coefficient of friction (μ) = 0.3 
• Acceleration due to gravity (g) = 10 m/s²

The force of friction \( F_f \) opposing the motion is given by: \[ F_f = \mu \cdot N \] Where \( N \) is the normal force. For a block on a horizontal surface, the normal force is equal to the weight of the block: \[ N = m \cdot g = 10 \cdot 10 = 100 \, \text{N} \] Now, the frictional force is: \[ F_f = 0.3 \cdot 100 = 30 \, \text{N} \] According to Newton's second law, the applied force \( F_{\text{applied}} \) is the sum of the frictional force and the force required to accelerate the block: \[ F_{\text{applied}} = F_f + F_{\text{required}} = 30 + m \cdot a \] The force required to accelerate the block is: \[ F_{\text{required}} = m \cdot a = 10 \cdot 3 = 30 \, \text{N} \] So the total applied force is: \[ F_{\text{applied}} = 30 + 30 = 60 \, \text{N} \]

Correct Answer:

Correct Answer: (C) 80 N