Physics 2016 JAMB Past Questions - Question 9: An object of mass 80 kg is pulled on a horizontal rough ground by a force of 500 N .Find the coefficient of static friction

Correct Answer

A

Explanation

To find the coefficient of static friction, we need to use the equation of motion for an object being pulled on a horizontal rough ground. The equation is:

F_applied - F_friction = m * a

Where:
F_applied is the applied force (500 N in this case)
F_friction is the force of friction
m is the mass of the object (80 kg in this case)
a is the acceleration of the object (which we assume to be zero since it is not mentioned)

Since the object is not accelerating, the equation becomes:

F_applied - F_friction = 0

We can rearrange the equation to solve for the force of friction:

F_friction = F_applied

Now, we can substitute the values into the equation:

F_friction = 500 N

The force of friction can be calculated using the equation:

F_friction = μ * N

Where:
μ is the coefficient of static friction
N is the normal force

Since the object is on a horizontal surface, the normal force is equal to the weight of the object, which is given by:

N = m * g

Where:
m is the mass of the object (80 kg)
g is the acceleration due to gravity (approximately 9.8 m/s^2)

Substituting the values, we get:

N = 80 kg * 9.8 m/s^2
N = 784 N

Now, we can substitute the values of F_friction and N into the equation for the force of friction:

500 N = μ * 784 N

Simplifying the equation, we find:

μ = 500 N / 784 N
μ ≈ 0.6378

Therefore, the coefficient of static friction is approximately 0.6378.